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Date:   Tue, 8 Feb 2022 09:59:31 +0100
From:   Jacopo Mondi <jacopo@jmondi.org>
To:     Eugen.Hristev@microchip.com
Cc:     robh+dt@kernel.org, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, jacopo+renesas@jmondi.org,
        hverkuil-cisco@xs4all.nl, Nicolas.Ferre@microchip.com,
        sakari.ailus@iki.fi, laurent.pinchart@ideasonboard.com
Subject: Re: [PATCH v4 03/11] media: atmel: atmel-isc: implement media
 controller
Message-ID: <20220208085931.5rf5dueyb57zxlyk@uno.localdomain>
References: <20220121131416.603972-1-eugen.hristev@microchip.com>
 <20220121131416.603972-4-eugen.hristev@microchip.com>
 <20220207124444.giyamcg2dgn6t3hv@uno.localdomain>
 <b456d5d5-e1ed-c896-482c-00598f92605f@microchip.com>
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In-Reply-To: <b456d5d5-e1ed-c896-482c-00598f92605f@microchip.com>
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Hi Eugen

On Mon, Feb 07, 2022 at 01:40:31PM +0000, Eugen.Hristev@microchip.com wrote:
> On 2/7/22 2:44 PM, Jacopo Mondi wrote:
> > Hi Eugen
> >
> > On Fri, Jan 21, 2022 at 03:14:08PM +0200, Eugen Hristev wrote:
> >> Implement the support for media-controller.
> >> This means that the capabilities of the driver have changed and now
> >> it also advertises the IO_MC .
> >> The driver will register it's media device, and add the video entity to this
> >> media device. The subdevices are registered to the same media device.
> >> The ISC will have a base entity which is auto-detected as atmel_isc_base.
> >> It will also register a subdevice that allows cropping of the incoming frame
> >> to the maximum frame size supported by the ISC.
> >> The ISC will create a link between the subdevice that is asynchronously
> >> registered and the atmel_isc_scaler entity.
> >> Then, the atmel_isc_scaler and atmel_isc_base are connected through another
> >> link.
> >>
> >> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> >> ---
> >> Changes in v4:
> >> As suggested by Jacopo:
> >> - renamed atmel_isc_mc to atmel_isc_scaler.c
> >> - moved init_mc/clean_mc to isc_base file
> >>
> >> Changes in v2:
> >> - implement try formats
> >>
> >>   drivers/media/platform/atmel/Makefile         |   2 +-
> >>   drivers/media/platform/atmel/atmel-isc-base.c |  73 +++++-
> >>   .../media/platform/atmel/atmel-isc-scaler.c   | 245 ++++++++++++++++++
> >>   drivers/media/platform/atmel/atmel-isc.h      |  37 +++
> >>   .../media/platform/atmel/atmel-sama5d2-isc.c  |  14 +-
> >>   .../media/platform/atmel/atmel-sama7g5-isc.c  |  12 +-
> >>   6 files changed, 375 insertions(+), 8 deletions(-)
> >>   create mode 100644 drivers/media/platform/atmel/atmel-isc-scaler.c
> >>
> >> diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
> >> index 794e8f739287..f02d03df89d6 100644
> >> --- a/drivers/media/platform/atmel/Makefile
> >> +++ b/drivers/media/platform/atmel/Makefile
> >> @@ -1,7 +1,7 @@
> >>   # SPDX-License-Identifier: GPL-2.0-only
> >>   atmel-isc-objs = atmel-sama5d2-isc.o
> >>   atmel-xisc-objs = atmel-sama7g5-isc.o
> >> -atmel-isc-common-objs = atmel-isc-base.o atmel-isc-clk.o
> >> +atmel-isc-common-objs = atmel-isc-base.o atmel-isc-clk.o atmel-isc-scaler.o
> >>
> >>   obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
> >>   obj-$(CONFIG_VIDEO_ATMEL_ISC_BASE) += atmel-isc-common.o
> >> diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
> >> index 6b0005987a17..6b482270eb93 100644
> >> --- a/drivers/media/platform/atmel/atmel-isc-base.c
> >> +++ b/drivers/media/platform/atmel/atmel-isc-base.c
> >> @@ -1710,6 +1710,7 @@ static int isc_async_bound(struct v4l2_async_notifier *notifier,
> >>                                              struct isc_device, v4l2_dev);
> >>        struct isc_subdev_entity *subdev_entity =
> >>                container_of(notifier, struct isc_subdev_entity, notifier);
> >> +     int pad;
> >>
> >>        if (video_is_registered(&isc->video_dev)) {
> >>                v4l2_err(&isc->v4l2_dev, "only supports one sub-device.\n");
> >> @@ -1718,6 +1719,16 @@ static int isc_async_bound(struct v4l2_async_notifier *notifier,
> >>
> >>        subdev_entity->sd = subdev;
> >>
> >> +     pad = media_entity_get_fwnode_pad(&subdev->entity, asd->match.fwnode,
> >> +                                       MEDIA_PAD_FL_SOURCE);
> >> +     if (pad < 0) {
> >> +             v4l2_err(&isc->v4l2_dev, "failed to find pad for %s\n",
> >> +                      subdev->name);
> >> +             return pad;
> >> +     }
> >> +
> >> +     isc->remote_pad = pad;
> >> +
> >>        return 0;
> >>   }
> >>
> >> @@ -1732,8 +1743,8 @@ static void isc_async_unbind(struct v4l2_async_notifier *notifier,
> >>        v4l2_ctrl_handler_free(&isc->ctrls.handler);
> >>   }
> >>
> >> -static struct isc_format *find_format_by_code(struct isc_device *isc,
> >> -                                           unsigned int code, int *index)
> >> +struct isc_format *isc_find_format_by_code(struct isc_device *isc,
> >> +                                        unsigned int code, int *index)
> >>   {
> >>        struct isc_format *fmt = &isc->formats_list[0];
> >>        unsigned int i;
> >> @@ -1749,6 +1760,7 @@ static struct isc_format *find_format_by_code(struct isc_device *isc,
> >>
> >>        return NULL;
> >>   }
> >> +EXPORT_SYMBOL_GPL(isc_find_format_by_code);
> >>
> >>   static int isc_formats_init(struct isc_device *isc)
> >>   {
> >> @@ -1765,7 +1777,7 @@ static int isc_formats_init(struct isc_device *isc)
> >>               NULL, &mbus_code)) {
> >>                mbus_code.index++;
> >>
> >> -             fmt = find_format_by_code(isc, mbus_code.code, &i);
> >> +             fmt = isc_find_format_by_code(isc, mbus_code.code, &i);
> >>                if (!fmt) {
> >>                        v4l2_warn(&isc->v4l2_dev, "Mbus code %x not supported\n",
> >>                                  mbus_code.code);
> >> @@ -1891,7 +1903,8 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier)
> >>        vdev->queue             = q;
> >>        vdev->lock              = &isc->lock;
> >>        vdev->ctrl_handler      = &isc->ctrls.handler;
> >> -     vdev->device_caps       = V4L2_CAP_STREAMING | V4L2_CAP_VIDEO_CAPTURE;
> >> +     vdev->device_caps       = V4L2_CAP_STREAMING | V4L2_CAP_VIDEO_CAPTURE |
> >> +                               V4L2_CAP_IO_MC;
> >>        video_set_drvdata(vdev, isc);
> >>
> >>        ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
> >> @@ -1901,8 +1914,18 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier)
> >>                goto isc_async_complete_err;
> >>        }
> >>
> >> +     ret = isc_scaler_link(isc);
> >> +     if (ret < 0)
> >> +             goto isc_async_complete_unregister_device;
> >> +
> >> +     ret = media_device_register(&isc->mdev);
> >> +     if (ret < 0)
> >> +             goto isc_async_complete_unregister_device;
> >>        return 0;
> >>
> >> +isc_async_complete_unregister_device:
> >> +     video_unregister_device(vdev);
> >> +
> >>   isc_async_complete_err:
> >>        mutex_destroy(&isc->lock);
> >>        return ret;
> >> @@ -1969,6 +1992,48 @@ int isc_pipeline_init(struct isc_device *isc)
> >>   }
> >>   EXPORT_SYMBOL_GPL(isc_pipeline_init);
> >>
> >> +int isc_mc_init(struct isc_device *isc, u32 ver)
> >> +{
> >> +     const struct of_device_id *match;
> >> +     int ret;
> >> +
> >> +     isc->video_dev.entity.function = MEDIA_ENT_F_IO_V4L;
> >> +     isc->video_dev.entity.flags = MEDIA_ENT_FL_DEFAULT;
> >
> > Should you set entity.ops.link_validate = v4l2_subdev_link_validate
> > to be able to have the media pipeline validated at
> > media_pipeline_start() time ?
>
> Hi,
>
> I am doing that in a subsequent patch. Things are not completely ready
> at this moment, because ISC still relies on the old mechanism to call
> v4l2_subdev_call with set_fmt on the subdevice (which subsequent patch
> removes and adds checks to the link validate ).
>

I see.. the subsequent patches are not part of this series, right ?

I think patches 1, 2, 4, 5 and 6 from this series do not depend on
the introduction of media controller or the scaler, right ? (I'm not
sure if the DTS patches do).

If that's the case, would it make sense to to fast-track them (as some
of them are fixes) and then on top plumb the media controller
infrastructure with this patch and the ones you have been mentioning ?

> >
> >> +     isc->pads[ISC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> >> +
> >> +     ret = media_entity_pads_init(&isc->video_dev.entity, ISC_PADS_NUM,
> >> +                                  isc->pads);
> >> +     if (ret < 0) {
> >> +             dev_err(isc->dev, "media entity init failed\n");
> >> +             return ret;
> >> +     }
> >> +
> >> +     isc->mdev.dev = isc->dev;
> >> +
> >> +     match = of_match_node(isc->dev->driver->of_match_table,
> >> +                           isc->dev->of_node);
> >> +
> >> +     strscpy(isc->mdev.driver_name, KBUILD_MODNAME,
> >> +             sizeof(isc->mdev.driver_name));
> >> +     strscpy(isc->mdev.model, match->compatible, sizeof(isc->mdev.model));
> >> +     snprintf(isc->mdev.bus_info, sizeof(isc->mdev.bus_info), "platform:%s",
> >> +              isc->v4l2_dev.name);
> >> +     isc->mdev.hw_revision = ver;
> >> +
> >> +     media_device_init(&isc->mdev);
> >> +
> >> +     isc->v4l2_dev.mdev = &isc->mdev;
> >> +
> >> +     return isc_scaler_init(isc);
> >> +}
> >> +EXPORT_SYMBOL_GPL(isc_mc_init);
> >> +
> >> +void isc_mc_cleanup(struct isc_device *isc)
> >> +{
> >> +     media_entity_cleanup(&isc->video_dev.entity);
> >> +}
> >> +EXPORT_SYMBOL_GPL(isc_mc_cleanup);
> >> +
> >>   /* regmap configuration */
> >>   #define ATMEL_ISC_REG_MAX    0xd5c
> >>   const struct regmap_config isc_regmap_config = {
> >> diff --git a/drivers/media/platform/atmel/atmel-isc-scaler.c b/drivers/media/platform/atmel/atmel-isc-scaler.c
> >> new file mode 100644
> >> index 000000000000..ec95c9665883
> >> --- /dev/null
> >> +++ b/drivers/media/platform/atmel/atmel-isc-scaler.c
> >> @@ -0,0 +1,245 @@
> >> +// SPDX-License-Identifier: GPL-2.0-only
> >> +/*
> >> + * Microchip Image Sensor Controller (ISC) Scaler entity support
> >> + *
> >> + * Copyright (C) 2021 Microchip Technology, Inc.
> >
> > Time flies! It's 2022 already :)
> >
> >> + *
> >> + * Author: Eugen Hristev <eugen.hristev@microchip.com>
> >> + *
> >> + */
> >> +
> >> +#include <media/media-device.h>
> >> +#include <media/media-entity.h>
> >> +#include <media/v4l2-device.h>
> >> +#include <media/v4l2-subdev.h>
> >> +
> >> +#include "atmel-isc-regs.h"
> >> +#include "atmel-isc.h"
> >> +
> >> +static int isc_scaler_get_fmt(struct v4l2_subdev *sd,
> >> +                           struct v4l2_subdev_state *sd_state,
> >> +                           struct v4l2_subdev_format *format)
> >> +{
> >> +     struct isc_device *isc = container_of(sd, struct isc_device, scaler_sd);
> >> +     struct v4l2_mbus_framefmt *v4l2_try_fmt;
> >> +
> >> +     if (format->which == V4L2_SUBDEV_FORMAT_TRY) {
> >> +             v4l2_try_fmt = v4l2_subdev_get_try_format(sd, sd_state,
> >> +                                                       format->pad);
> >> +             format->format = *v4l2_try_fmt;
> >> +
> >> +             return 0;
> >> +     }
> >> +
> >> +     format->format = isc->scaler_format;
> >
> > isc->scaler_format is only used inside this file if I'm not mistaken.
> > I wonder why it lives in the isc_device struct.
>
> isc_device is a placeholder for all isc things.
>
> I would not create a separate struct in this file that would have to be
> allocated etc... just for one two things. So I preferred to have it in
> the same place as all the other things.
>
> >
> >> +
> >> +     return 0;
> >> +}
> >> +
> >> +static int isc_scaler_set_fmt(struct v4l2_subdev *sd,
> >> +                           struct v4l2_subdev_state *sd_state,
> >> +                           struct v4l2_subdev_format *req_fmt)
> >> +{
> >> +     struct isc_device *isc = container_of(sd, struct isc_device, scaler_sd);
> >> +     struct v4l2_mbus_framefmt *v4l2_try_fmt;
> >> +     struct isc_format *fmt;
> >> +     unsigned int i;
> >> +
> >> +     if (req_fmt->pad == ISC_SCALER_PAD_SOURCE)
> >> +             v4l_bound_align_image
> >> +                     (&req_fmt->format.width, 16, isc->max_width, 0,
> >> +                      &req_fmt->format.height, 16, isc->max_height, 0, 0);
> >> +     else
> >> +             v4l_bound_align_image
> >> +                     (&req_fmt->format.width, 16, 10000, 0,
> >> +                      &req_fmt->format.height, 16, 10000, 0, 0);
> >
> > Where does 10000 come from ?
>
> It's a random number. Do you have any suggestion for a better one ?

An actual HW limit ? :)

> Maybe this would be much more clear with my comments below (where I will
> explain what the isc scaler does )
> In short, it allows the other entity in the link to 'sink' a huge format
> into this 'scaler' . Because the scaler can crop anything basically down
> to the biggest format size the ISC could handle.
>

doesn't it have any documented input size limit ?

> >
> >> +
> >> +     req_fmt->format.colorspace = V4L2_COLORSPACE_SRGB;
> >> +     req_fmt->format.field = V4L2_FIELD_NONE;
> >> +     req_fmt->format.ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> >> +     req_fmt->format.quantization = V4L2_QUANTIZATION_DEFAULT;
> >> +     req_fmt->format.xfer_func = V4L2_XFER_FUNC_DEFAULT;
> >> +
> >> +     fmt = isc_find_format_by_code(isc, req_fmt->format.code, &i);
> >
> > So you rely on the isc format list for the scaler as well ?
> > I think it's fine as long as they are identical
>
> Yes, the scaler is kind of a dummy entity , but it's required by the
> media controller validation of the pipeline.
>

More on this later

> >
> >> +
> >> +     if (!fmt)
> >> +             fmt = &isc->formats_list[0];
> >> +
> >> +     req_fmt->format.code = fmt->mbus_code;
> >> +
> >> +     if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY) {
> >> +             v4l2_try_fmt = v4l2_subdev_get_try_format(sd, sd_state,
> >> +                                                       req_fmt->pad);
> >> +             *v4l2_try_fmt = req_fmt->format;
> >> +             /* Trying on the pad sink makes the source sink change too */
> >> +             if (req_fmt->pad == ISC_SCALER_PAD_SINK) {
> >> +                     v4l2_try_fmt =
> >> +                             v4l2_subdev_get_try_format(sd, sd_state,
> >> +                                                        ISC_SCALER_PAD_SOURCE);
> >> +                     *v4l2_try_fmt = req_fmt->format;
> >> +
> >> +                     v4l_bound_align_image(&v4l2_try_fmt->width,
> >> +                                           16, isc->max_width, 0,
> >> +                                           &v4l2_try_fmt->height,
> >> +                                           16, isc->max_height, 0, 0);
> >> +             }
> >> +             /* if we are just trying, we are done */
> >> +             return 0;
> >> +     }
> >> +
> >> +     isc->scaler_format = req_fmt->format;
> >
> > No per-pad format but a global scaler_format ? How do you configure scaling ?
> >
> > Actually, I would like to know more about the scaler device
> > capabilities. What functions can this IP perform ? Does it do
> > cropping, can it also do (down)scaling or even composition ?
> >
> > I think it is worth to read
> > https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/dev-subdev.html#v4l2-subdev-selections
> > where it is reported how cropping and scaling are implemented by using
> > the selection API.
> >
> > Figure 4.5 is particularly helpful to explain the simple crop case,
> > for which you need to implement support to by adding s_selection on
> > the sink pad TGT_CROP target.
>
> The scaler is kind of a dummy entity.
> The problem is that different subdevices cannot be connected directly to
> a v4l entity, because the ISC does cropping on the incoming frame.
> The ISC has a limit on the total number of pixels per frame, thus it
> will do a crop.

What is this limit related to ? I don't know the ISC internals, but is
the limitation due to the overall image size, or maybe it's due to
some line buffers being limited in the size they can transfer to
memory ? Is it a limitation on the size of the image in pixels, or is
it due to a limitation of the processing bandwidth on the input
interface and thus depends on the actual size of the image in bytes ?

> So, if I allow e.g. an entity that sends 3280x2464 , when the ISC can
> only handle 3264x2464 , then we have two choices:
> 1/ crop it and output the 3264x2464 -> cannot, because userspace expects
> 3280x2464, and the whole pipeline fails to configure, there is a
> mismatch between /dev/video output and what the whole pipeline produces

I'm confused in first place. If the ISC cannot output anything larger
than 3264x2464, then if userspace sets a 3280x2464 size on the ISC,
this should be adjusted to 3264x2464.

Or is the ISC limitation on the -input- side ?

> 2/ deny the link, and ask the subdevice to produce the 3264x2464 which
> the ISC can handle at most -> cannot , because the sensor let's say can
> *only* produce 3280x2464 and *any* other frame size returns an error.

buggy sensor I would say :)

>
> The only solution to make both worlds happy, is to have a dummy entity
> called 'scaler' which in fact now it only performs a simple crop.
> It accepts any frame size at input (hence the 10000x10000 which you saw
> earlier), and outputs at most 3264x2464 the isc_max_height and
> isc_max_width.

I have a maybe dumb question: can the cropping operation be modeled
by applying a TGT_CROP rectangle (whose _BOUND size is 3280x2464) to
the atmel_isc_common entity sink pad and avoid the scaler completely ?

>
> So to answer your question, the isc scaler is a software model for a
> simple cropping, that would make media controller happy, and capture
> software happy.
>
> Here it how it looks :
>
> Device topology
> - entity 1: atmel_isc_scaler (2 pads, 2 links)
>              type V4L2 subdev subtype Unknown flags 0
>              device node name /dev/v4l-subdev0
>          pad0: Sink
>                  [fmt:SRGGB10_1X10/3280x2464 field:none colorspace:srgb
>                   crop.bounds:(0,0)/3264x2464
>                   crop:(0,0)/3264x2464]
>                  <- "csi2dc":1 [ENABLED,IMMUTABLE]
>          pad1: Source
>                  [fmt:SRGGB10_1X10/3280x2464 field:none colorspace:srgb]
>                  -> "atmel_isc_common":0 [ENABLED,IMMUTABLE]
>
> - entity 4: csi2dc (2 pads, 2 links)
>              type V4L2 subdev subtype Unknown flags 0
>              device node name /dev/v4l-subdev1
>          pad0: Sink
>                  [fmt:SRGGB10_1X10/3280x2464 field:none colorspace:srgb]
>                  <- "dw-csi.0":1 [ENABLED]
>          pad1: Source
>                  [fmt:SRGGB10_1X10/3280x2464 field:none colorspace:srgb]
>                  -> "atmel_isc_scaler":0 [ENABLED,IMMUTABLE]
>
> - entity 7: dw-csi.0 (2 pads, 2 links)
>              type V4L2 subdev subtype Unknown flags 0
>              device node name /dev/v4l-subdev2
>          pad0: Sink
>                  [fmt:SRGGB10_1X10/3280x2464]
>                  <- "imx219 1-0010":0 [ENABLED]
>          pad1: Source
>                  [fmt:SRGGB10_1X10/3280x2464]
>                  -> "csi2dc":0 [ENABLED]
>
> - entity 12: imx219 1-0010 (1 pad, 1 link)
>               type V4L2 subdev subtype Sensor flags 0
>               device node name /dev/v4l-subdev3
>          pad0: Source
>                  [fmt:SRGGB10_1X10/3280x2464 field:none colorspace:srgb
> xfer:srgb ycbcr:601 quantization:full-range
>                   crop.bounds:(8,8)/3280x2464
>                   crop:(8,8)/3280x2464]
>                  -> "dw-csi.0":0 [ENABLED]
>
> - entity 24: atmel_isc_common (1 pad, 1 link)
>               type Node subtype V4L flags 1
>               device node name /dev/video0
>          pad0: Sink
>                  <- "atmel_isc_scaler":1 [ENABLED,IMMUTABLE]
>
>
> Scaler does this one cute little thing :
>
>    	pad0: Sink
>                  [fmt:SRGGB10_1X10/3280x2464 field:none colorspace:srgb
>                   crop.bounds:(0,0)/3264x2464
>                   crop:(0,0)/3264x2464]
>                  <- "csi2dc":1 [ENABLED,IMMUTABLE]
>          pad1: Source
>                  [fmt:SRGGB10_1X10/3280x2464 field:none colorspace:srgb]

Shouldn't this be 3264x2464 as that's what the entity outputs after
the cropping ? And shouldn't then be 3264x2464 the size output from
the video device too ?


>                  -> "atmel_isc_common":0 [ENABLED,IMMUTABLE]
>
>
> Which is what we needed.
>
> >
> >> +
> >> +     return 0;
> >> +}
> >> +
> >> +static int isc_scaler_enum_mbus_code(struct v4l2_subdev *sd,
> >> +                                  struct v4l2_subdev_state *sd_state,
> >> +                                  struct v4l2_subdev_mbus_code_enum *code)
> >> +{
> >> +     struct isc_device *isc = container_of(sd, struct isc_device, scaler_sd);
> >> +     int supported_index = 0;
> >> +     int i;
> >> +
> >> +     for (i = 0; i < isc->formats_list_size; i++) {
> >> +             if (!isc->formats_list[i].sd_support)
> >> +                     continue;
> >
> > The sd_support flag still doesn't click in my head.
> >
> > Shouldn't the enumeration of available formats on the scaler do not
> > depend on the sensor supproted formats ?
>
> You're right. I will have to check it again.
>
> >
> >> +             if (supported_index == code->index) {
> >> +                     code->code = isc->formats_list[i].mbus_code;
> >> +                     return 0;
> >> +             }
> >> +             supported_index++;
> >> +     }
> >> +
> >> +     return -EINVAL;
> >> +}
> >> +
> >> +static int isc_scaler_g_sel(struct v4l2_subdev *sd,
> >> +                         struct v4l2_subdev_state *sd_state,
> >> +                         struct v4l2_subdev_selection *sel)
> >> +{
> >> +     struct isc_device *isc = container_of(sd, struct isc_device, scaler_sd);
> >> +
> >> +     if (sel->pad == ISC_SCALER_PAD_SOURCE)
> >> +             return -EINVAL;
> >> +
> >> +     if (sel->target != V4L2_SEL_TGT_CROP_BOUNDS &&
> >> +         sel->target != V4L2_SEL_TGT_CROP)
> >> +             return -EINVAL;
> >> +
> >> +     sel->r.height = isc->max_height;
> >> +     sel->r.width = isc->max_width;
> >
> > The CROP_BOUNDS should be set to the same size as the sink pad image format,
> > as it represents the maximum valid crop rectangle.
> >
> > TGT_CROP should report the configured crop rectangle which can be
> > intiialized to the same size as CROP_BOUNDS, if my understanding of
> > the spec is correct
>
> So you would like to have this differentiated, and report the
> CROP_BOUNDS to whatever is on the sink pad, and the TGT_CROP to what is
> reported now, the maximum size of the ISC frame .
> My understanding is correct ?
>

I didn't know you have an HW limitation, so your _BOUNDS is not the
input image size but rather 3264x2464 ( == max_width x max_height).

What I meant is that _BOUNDS should report the maximum rectangle size
that can be applied to the _CROP target. In you case you have an HW
limitation 3264x2464 and that's the largest rectangle you can apply.
TGT_CROP can be initialized to the same as _BOUND, but if you
implement s_selection it should report what has been there applied.
But as you don't implement s_selection yet, I think this is fine for
now. Maybe a little comment ?

Also, is set->r zeroed by the framework before getting here ?
Otherwise you should set r.left and r.top to 0

> >
> >> +
> >> +     sel->r.left = 0;
> >> +     sel->r.top = 0;
> >> +
> >> +     return 0;
> >> +}
> >> +
> >> +static int isc_scaler_init_cfg(struct v4l2_subdev *sd,
> >> +                            struct v4l2_subdev_state *sd_state)
> >> +{
> >> +     struct v4l2_mbus_framefmt *v4l2_try_fmt =
> >> +             v4l2_subdev_get_try_format(sd, sd_state, 0);
> >> +     struct isc_device *isc = container_of(sd, struct isc_device, scaler_sd);
> >> +
> >> +     *v4l2_try_fmt = isc->scaler_format;
> >> +
> >> +     return 0;
> >> +}
> >> +
> >> +static const struct v4l2_subdev_pad_ops isc_scaler_pad_ops = {
> >> +     .enum_mbus_code = isc_scaler_enum_mbus_code,
> >> +     .set_fmt = isc_scaler_set_fmt,
> >> +     .get_fmt = isc_scaler_get_fmt,
> >> +     .get_selection = isc_scaler_g_sel,
> >> +     .init_cfg = isc_scaler_init_cfg,
> >
> > .link_validate = v4l2_subdev_link_validate_default,
> >
> > To have the formats at the end of links that point to this entity
> > validated (I think the framework already calls it if not set though,
> > please check v4l2-subdev.c:v4l2_subdev_link_validate())
> >
> >> +};
> >> +
> >> +static const struct v4l2_subdev_ops xisc_scaler_subdev_ops = {
> >> +     .pad = &isc_scaler_pad_ops,
> >> +};
> >> +
> >> +int isc_scaler_init(struct isc_device *isc)
> >> +{
> >> +     int ret;
> >> +
> >> +     v4l2_subdev_init(&isc->scaler_sd, &xisc_scaler_subdev_ops);
> >> +
> >> +     isc->scaler_sd.owner = THIS_MODULE;
> >> +     isc->scaler_sd.dev = isc->dev;
> >> +     snprintf(isc->scaler_sd.name, sizeof(isc->scaler_sd.name),
> >> +              "atmel_isc_scaler");
> >
> > I would drop 'atmel' for brevity, unless other entities have this
> > prefix set already
>
> The v4l entity takes it's name from the module name, which is
> atmel_isc_common, so I thought to keep the prefix
>

Ack!

> >
> >> +
> >> +     isc->scaler_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> >> +     isc->scaler_sd.entity.function = MEDIA_ENT_F_PROC_VIDEO_SCALER;
> >> +     isc->scaler_pads[ISC_SCALER_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> >> +     isc->scaler_pads[ISC_SCALER_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
> >> +
> >> +     isc->scaler_format.height = isc->max_height;
> >> +     isc->scaler_format.width = isc->max_width;
> >> +     isc->scaler_format.code = isc->formats_list[0].mbus_code;
> >> +     isc->scaler_format.colorspace = V4L2_COLORSPACE_SRGB;
> >> +     isc->scaler_format.field = V4L2_FIELD_NONE;
> >> +     isc->scaler_format.ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> >> +     isc->scaler_format.quantization = V4L2_QUANTIZATION_DEFAULT;
> >> +     isc->scaler_format.xfer_func = V4L2_XFER_FUNC_DEFAULT;
> >> +
> >> +     ret = media_entity_pads_init(&isc->scaler_sd.entity,
> >> +                                  ISC_SCALER_PADS_NUM,
> >> +                                  isc->scaler_pads);
> >> +     if (ret < 0) {
> >> +             dev_err(isc->dev, "scaler sd media entity init failed\n");
> >> +             return ret;
> >> +     }
> >> +     ret = v4l2_device_register_subdev(&isc->v4l2_dev, &isc->scaler_sd);
> >> +     if (ret < 0) {
> >> +             dev_err(isc->dev, "scaler sd failed to register subdev\n");
> >> +             return ret;
> >> +     }
> >> +
> >> +     return ret;
> >> +}
> >> +EXPORT_SYMBOL_GPL(isc_scaler_init);
> >> +
> >> +int isc_scaler_link(struct isc_device *isc)
> >> +{
> >> +     int ret;
> >> +
> >> +     ret = media_create_pad_link(&isc->current_subdev->sd->entity,
> >> +                                 isc->remote_pad, &isc->scaler_sd.entity,
> >> +                                 ISC_SCALER_PAD_SINK,
> >> +                                 MEDIA_LNK_FL_ENABLED |
> >> +                                 MEDIA_LNK_FL_IMMUTABLE);
> >> +
> >> +     if (ret < 0) {
> >> +             v4l2_err(&isc->v4l2_dev,
> >> +                      "Failed to create pad link: %s to %s\n",
> >> +                      isc->current_subdev->sd->entity.name,
> >> +                      isc->scaler_sd.entity.name);
> >> +             return ret;
> >> +     }
> >> +
> >> +     dev_dbg(isc->dev, "link with %s pad: %d\n",
> >> +             isc->current_subdev->sd->name, isc->remote_pad);
> >> +
> >> +     ret = media_create_pad_link(&isc->scaler_sd.entity,
> >> +                                 ISC_SCALER_PAD_SOURCE,
> >> +                                 &isc->video_dev.entity, ISC_PAD_SINK,
> >> +                                 MEDIA_LNK_FL_ENABLED |
> >> +                                 MEDIA_LNK_FL_IMMUTABLE);
> >> +
> >> +     if (ret < 0) {
> >> +             v4l2_err(&isc->v4l2_dev,
> >> +                      "Failed to create pad link: %s to %s\n",
> >> +                      isc->scaler_sd.entity.name,
> >> +                      isc->video_dev.entity.name);
> >> +             return ret;
> >> +     }
> >> +
> >> +     dev_dbg(isc->dev, "link with %s pad: %d\n", isc->scaler_sd.name,
> >> +             ISC_SCALER_PAD_SOURCE);
> >> +
> >> +     return ret;
> >> +}
> >> +EXPORT_SYMBOL_GPL(isc_scaler_link);
> >
> >  From the DT graph point of view, the ISC appears as a single block
> > with an CSI-2 input port. It is then in charge of parsing the .dts and
> > add to its notifier the image sensor remote subdevice.
>
> Actually it's only a parallel port.
> And it can be connected either to a sensor directly or to the csi2dc
> bridge. (the csi2dc bridge can be connected to a CSI-2 receiver)
>
> >
> > When the sensor subdev registers and the ISC notifier completes, the scaler
> > entity which was initialized at isc_probe() time is linked in between
> > the ISC and the image sensor immutably.
>
> yes, because this cannot change at runtime, and usually, it can't change
> without altering the board hardware. (at least this is what my
> understanding of immutability is )
>
> >
> > I think it is fine for now, but I wonder if you plan to plumb more
> > components between the ISC video node and the sensor, if it's not
> > worth changing the DT bindings and their parsing logic to separate the
> > CSI-2 receiver from the ISC, whcih can create its media graph at probe
> > time and have the CSI-2 receiver entity as downstream remote. I think
> > I need to get to know the ISC better to really have an idea. For now,
> > this seems ok to me, but please check with maintainers if this is fine
> > with them.
>
> In the XISC case (sama7g5-isc), the csi2dc receiver is the subdev (so,
> the remote subdev).
> The ISC will register a scaler, and connect the subdev to this scaler
> first, and then, the scaler to the isc itself (the v4l entity).
>
> >
> >> +
> >> diff --git a/drivers/media/platform/atmel/atmel-isc.h b/drivers/media/platform/atmel/atmel-isc.h
> >> index 5fbf52a9080b..c9234c90ae58 100644
> >> --- a/drivers/media/platform/atmel/atmel-isc.h
> >> +++ b/drivers/media/platform/atmel/atmel-isc.h
> >> @@ -183,6 +183,17 @@ struct isc_reg_offsets {
> >>        u32 his_entry;
> >>   };
> >>
> >> +enum isc_mc_pads {
> >> +     ISC_PAD_SINK    = 0,
> >> +     ISC_PADS_NUM    = 1,
> >> +};
> >> +
> >> +enum isc_scaler_pads {
> >> +     ISC_SCALER_PAD_SINK     = 0,
> >> +     ISC_SCALER_PAD_SOURCE   = 1,
> >> +     ISC_SCALER_PADS_NUM     = 2,
> >> +};
> >> +
> >>   /*
> >>    * struct isc_device - ISC device driver data/config struct
> >>    * @regmap:          Register map
> >> @@ -257,6 +268,12 @@ struct isc_reg_offsets {
> >>    *                   be used as an input to the controller
> >>    * @controller_formats_size: size of controller_formats array
> >>    * @formats_list_size:       size of formats_list array
> >> + * @pads:            media controller pads for isc video entity
> >> + * @mdev:            media device that is registered by the isc
> >> + * @remote_pad:              remote pad on the connected subdevice
> >> + * @scaler_sd:               subdevice for the scaler that isc registers
> >> + * @scaler_pads:     media controller pads for the scaler subdevice
> >> + * @scaler_format:   current format for the scaler subdevice
> >>    */
> >>   struct isc_device {
> >>        struct regmap           *regmap;
> >> @@ -344,6 +361,19 @@ struct isc_device {
> >>        struct isc_format               *formats_list;
> >>        u32                             controller_formats_size;
> >>        u32                             formats_list_size;
> >> +
> >> +     struct {
> >> +             struct media_pad                pads[ISC_PADS_NUM];
> >> +             struct media_device             mdev;
> >> +
> >> +             u32                             remote_pad;
> >> +     };
> >> +
> >> +     struct {
> >> +             struct v4l2_subdev              scaler_sd;
> >> +             struct media_pad                scaler_pads[ISC_SCALER_PADS_NUM];
> >> +             struct v4l2_mbus_framefmt       scaler_format;
>
> Here are the scaler stuff which I added, in the same bulk struct for the
> whole isc device
>
>
> >> +     };
> >>   };
> >>
> >>   extern const struct regmap_config isc_regmap_config;
> >> @@ -355,4 +385,11 @@ int isc_clk_init(struct isc_device *isc);
> >>   void isc_subdev_cleanup(struct isc_device *isc);
> >>   void isc_clk_cleanup(struct isc_device *isc);
> >>
> >> +int isc_scaler_link(struct isc_device *isc);
> >> +int isc_scaler_init(struct isc_device *isc);
> >> +int isc_mc_init(struct isc_device *isc, u32 ver);
> >> +void isc_mc_cleanup(struct isc_device *isc);
> >> +
> >> +struct isc_format *isc_find_format_by_code(struct isc_device *isc,
> >> +                                        unsigned int code, int *index);
> >>   #endif
> >> diff --git a/drivers/media/platform/atmel/atmel-sama5d2-isc.c b/drivers/media/platform/atmel/atmel-sama5d2-isc.c
> >> index c5b9563e36cb..c244682ea22f 100644
> >> --- a/drivers/media/platform/atmel/atmel-sama5d2-isc.c
> >> +++ b/drivers/media/platform/atmel/atmel-sama5d2-isc.c
> >> @@ -553,6 +553,12 @@ static int atmel_isc_probe(struct platform_device *pdev)
> >>                        break;
> >>        }
> >>
> >> +     regmap_read(isc->regmap, ISC_VERSION + isc->offsets.version, &ver);
> >
> > I am surprised you can read a register before runtime_pm is
> > intialized!
> >
>
> Actually I can read any register after the moment of starting the clock
> on the hardware block.

Ah right then

> Maybe the starting and stopping of the clock needs to be moved to the
> runtime_pm calls, but this is another story, not related to the media
> controller.

It's fine, but maybe worth recording with a todo ?

Thanks
  j

> I moved this line because I had to pass the version to the isc_mc_init call
>
> > Thanks
> >     j
>
> Thanks for reviewing !
> Eugen
> >
> >
> >> +
> >> +     ret = isc_mc_init(isc, ver);
> >> +     if (ret < 0)
> >> +             goto isc_probe_mc_init_err;
> >> +
> >>        pm_runtime_set_active(dev);
> >>        pm_runtime_enable(dev);
> >>        pm_request_idle(dev);
> >> @@ -562,7 +568,7 @@ static int atmel_isc_probe(struct platform_device *pdev)
> >>        ret = clk_prepare_enable(isc->ispck);
> >>        if (ret) {
> >>                dev_err(dev, "failed to enable ispck: %d\n", ret);
> >> -             goto cleanup_subdev;
> >> +             goto isc_probe_mc_init_err;
> >>        }
> >>
> >>        /* ispck should be greater or equal to hclock */
> >> @@ -572,7 +578,6 @@ static int atmel_isc_probe(struct platform_device *pdev)
> >>                goto unprepare_clk;
> >>        }
> >>
> >> -     regmap_read(isc->regmap, ISC_VERSION + isc->offsets.version, &ver);
> >>        dev_info(dev, "Microchip ISC version %x\n", ver);
> >>
> >>        return 0;
> >> @@ -580,6 +585,9 @@ static int atmel_isc_probe(struct platform_device *pdev)
> >>   unprepare_clk:
> >>        clk_disable_unprepare(isc->ispck);
> >>
> >> +isc_probe_mc_init_err:
> >> +     isc_mc_cleanup(isc);
> >> +
> >>   cleanup_subdev:
> >>        isc_subdev_cleanup(isc);
> >>
> >> @@ -600,6 +608,8 @@ static int atmel_isc_remove(struct platform_device *pdev)
> >>
> >>        pm_runtime_disable(&pdev->dev);
> >>
> >> +     isc_mc_cleanup(isc);
> >> +
> >>        isc_subdev_cleanup(isc);
> >>
> >>        v4l2_device_unregister(&isc->v4l2_dev);
> >> diff --git a/drivers/media/platform/atmel/atmel-sama7g5-isc.c b/drivers/media/platform/atmel/atmel-sama7g5-isc.c
> >> index 07a80b08bc54..9dc75eed0098 100644
> >> --- a/drivers/media/platform/atmel/atmel-sama7g5-isc.c
> >> +++ b/drivers/media/platform/atmel/atmel-sama7g5-isc.c
> >> @@ -547,15 +547,23 @@ static int microchip_xisc_probe(struct platform_device *pdev)
> >>                        break;
> >>        }
> >>
> >> +     regmap_read(isc->regmap, ISC_VERSION + isc->offsets.version, &ver);
> >> +
> >> +     ret = isc_mc_init(isc, ver);
> >> +     if (ret < 0)
> >> +             goto isc_probe_mc_init_err;
> >> +
> >>        pm_runtime_set_active(dev);
> >>        pm_runtime_enable(dev);
> >>        pm_request_idle(dev);
> >>
> >> -     regmap_read(isc->regmap, ISC_VERSION + isc->offsets.version, &ver);
> >>        dev_info(dev, "Microchip XISC version %x\n", ver);
> >>
> >>        return 0;
> >>
> >> +isc_probe_mc_init_err:
> >> +     isc_mc_cleanup(isc);
> >> +
> >>   cleanup_subdev:
> >>        isc_subdev_cleanup(isc);
> >>
> >> @@ -576,6 +584,8 @@ static int microchip_xisc_remove(struct platform_device *pdev)
> >>
> >>        pm_runtime_disable(&pdev->dev);
> >>
> >> +     isc_mc_cleanup(isc);
> >> +
> >>        isc_subdev_cleanup(isc);
> >>
> >>        v4l2_device_unregister(&isc->v4l2_dev);
> >> --
> >> 2.25.1
> >>
>