by Lad, Prabhakar

[permalink] [raw]

Subject: Re: [Patch 05/13] media: am437x-vpfe: Streamlined vb2 buffer cleanup

On Mon, Sep 16, 2019 at 3:51 PM Benoit Parrot <[email protected]> wrote:
>
> Lad, Prabhakar <[email protected]> wrote on Mon [2019-Sep-16 09:00:03 +0100]:
> > Hi Benoit,
> >
> > Thank you for the patch.
> >
> > On Mon, Sep 9, 2019 at 5:26 PM Benoit Parrot <[email protected]> wrote:
> > >
> > > Returning queued vb2 buffers back to user space is a common
> > > task best handled by a helper function.
> > >
> > > Signed-off-by: Benoit Parrot <[email protected]>
> > > ---
> > > drivers/media/platform/am437x/am437x-vpfe.c | 54 ++++++++++-----------
> > > 1 file changed, 26 insertions(+), 28 deletions(-)
> > >
> > > diff --git a/drivers/media/platform/am437x/am437x-vpfe.c b/drivers/media/platform/am437x/am437x-vpfe.c
> > > index 3a8ad9bdf283..52f7fc6e11dd 100644
> > > --- a/drivers/media/platform/am437x/am437x-vpfe.c
> > > +++ b/drivers/media/platform/am437x/am437x-vpfe.c
> > > @@ -1949,6 +1949,29 @@ static void vpfe_buffer_queue(struct vb2_buffer *vb)
> > > spin_unlock_irqrestore(&vpfe->dma_queue_lock, flags);
> > > }
> > >
> > > +static void vpfe_return_all_buffers(struct vpfe_device *vpfe,
> > > + enum vb2_buffer_state state)
> > > +{
> > > + struct vpfe_cap_buffer *buf, *node;
> > > + unsigned long flags;
> > > +
> > > + spin_lock_irqsave(&vpfe->dma_queue_lock, flags);
> > > + list_for_each_entry_safe(buf, node, &vpfe->dma_queue, list) {
> > > + vb2_buffer_done(&buf->vb.vb2_buf, state);
> > > + list_del(&buf->list);
> > > + }
> > > +
> > > + if (vpfe->cur_frm)
> > > + vb2_buffer_done(&vpfe->cur_frm->vb.vb2_buf, state);
> > > +
> > > + if (vpfe->next_frm && vpfe->next_frm != vpfe->cur_frm)
> > > + vb2_buffer_done(&vpfe->next_frm->vb.vb2_buf, state);
> > > +
> > > + vpfe->cur_frm = NULL;
> > > + vpfe->next_frm = NULL;
> > > + spin_unlock_irqrestore(&vpfe->dma_queue_lock, flags);
> > > +}
> > > +
> > > /*
> > > * vpfe_start_streaming : Starts the DMA engine for streaming
> > > * @vb: ptr to vb2_buffer
> > > @@ -1957,7 +1980,6 @@ static void vpfe_buffer_queue(struct vb2_buffer *vb)
> > > static int vpfe_start_streaming(struct vb2_queue *vq, unsigned int count)
> > > {
> > > struct vpfe_device *vpfe = vb2_get_drv_priv(vq);
> > > - struct vpfe_cap_buffer *buf, *tmp;
> > > struct vpfe_subdev_info *sdinfo;
> > > unsigned long flags;
> > > unsigned long addr;
> > > @@ -2003,11 +2025,8 @@ static int vpfe_start_streaming(struct vb2_queue *vq, unsigned int count)
> > > return 0;
> > >
> > > err:
> > > - list_for_each_entry_safe(buf, tmp, &vpfe->dma_queue, list) {
> > > - list_del(&buf->list);
> > > - vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> > > - }
> > > -
> > > + vpfe_return_all_buffers(vpfe, VB2_BUF_STATE_QUEUED);
> > > + vpfe_pcr_enable(&vpfe->ccdc, 0);
> >
> > please create a seperate patch for the above change.
>
> You mean a separate patch just for the vpfe_pcr_enable() call?
>
yes, as the call to vpfe_pcr_enable() is to disable the CCDC and it
doesn't match the patch
description.

Cheers,
--Prabhakar Lad

2019-09-17 18:39:31

by Benoit Parrot

[permalink] [raw]

Subject: Re: [Patch 07/13] media: am437x-vpfe: Use a per instance format array instead of a static one

Hans Verkuil <[email protected]> wrote on Fri [2019-Sep-13 15:07:29 +0200]:
> On 9/9/19 6:27 PM, Benoit Parrot wrote:
> > +/*
> > + * This value needs to be at least as large as the number of entry in
> > + * formats[].
> > + * When formats[] is modified make sure to adjust this value also.
> > + */
> > +#define VPFE_MAX_ACTIVE_FMT 10
>
> I recommend adding something like:
>
> #if ARRAY_SIZE(formats) > VPFE_MAX_ACTIVE_FMT
> #error must update VPFE_MAX_ACTIVE_FMT
> #endif
>
> to am437x-vpfe.c.
>
> Or something along those lines. Don't rely on just the comment :-)

I remeber doing this a while back for another driver.
Not sure if you ever treid this or not but "#if ARRAY_SIZE()" construct
does not work because the ARRAY_SIZE() macro which needs to evaluate
sizeof() generates the following compiler error:

In file included from ../include/linux/delay.h:22,
from ../drivers/media/platform/am437x/am437x-vpfe.c:23:
../include/linux/kernel.h:47:26: warning: "sizeof" is not defined,
evaluates to 0 [-Wundef]
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) +
__must_be_array(arr))

So no luck there. But I remembered also how I previously fixed it.
In this case if instead of leaving the formats[] definition with empty
brackets you actually used the same defined value like
formats[VPFE_MAX_ACTIVE_FMT] then if you inadvertantly add more enties in
the table then the value of VPFE_MAX_ACTIVE_FMT then you'll get series of
compile time warnings like this:

drivers/media/platform/am437x/am437x-vpfe.c:108:5: warning: excess elements
in array initializer
}, {
^
drivers/media/platform/am437x/am437x-vpfe.c:108:5: note: (near initialization
for ‘formats’)
drivers/media/platform/am437x/am437x-vpfe.c:115:5: warning: excess elements
in array initializer
}, {

etc...

So this is how I will address this.

Benoit

>
> Regards,
>
> Hans
>