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Date:   Wed, 20 Jan 2021 14:40:28 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Michael Nazzareno Trimarchi <michael@amarulasolutions.com>
Cc:     Jagan Teki <jagan@amarulasolutions.com>,
        Rob Herring <robh+dt@kernel.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Sam Ravnborg <sam@ravnborg.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-amarula <linux-amarula@amarulasolutions.com>,
        Matteo Lisi <matteo.lisi@engicam.com>
Subject: Re: [PATCH 2/2] drm: bridge: Add SN65DSI84 DSI to LVDS bridge
Message-ID: <YAgkvE4UvLUKbjz0@pendragon.ideasonboard.com>
References: <20210120112158.62109-1-jagan@amarulasolutions.com>
 <20210120112158.62109-2-jagan@amarulasolutions.com>
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On Wed, Jan 20, 2021 at 12:55:40PM +0100, Michael Nazzareno Trimarchi wrote:
> On Wed, Jan 20, 2021 at 12:29 PM Jagan Teki wrote:
> > On Wed, Jan 20, 2021 at 4:55 PM Michael Nazzareno Trimarchi wrote:
> > > On Wed, Jan 20, 2021 at 12:22 PM Jagan Teki wrote:
> > > >
> > > > SN65DSI84 is a Single Channel DSI to Dual-link LVDS bridge from
> > > > Texas Instruments.
> > > >
> > > > SN65DSI83, SN65DSI85 are variants of the same family of bridge
> > > > controllers.
> > > >
> > > > Right now the bridge driver is supporting a single link, dual-link
> > > > support requires to initiate I2C Channel B registers.
> > > >
> > > > Tested with STM32MP1 MIPI DSI host design configuration.
> > > >
> > > > Signed-off-by: Matteo Lisi <matteo.lisi@engicam.com>
> > > > Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> > > > ---
> > > >  MAINTAINERS                           |   6 +
> > > >  drivers/gpu/drm/bridge/Kconfig        |  19 +
> > > >  drivers/gpu/drm/bridge/Makefile       |   1 +
> > > >  drivers/gpu/drm/bridge/ti-sn65dsi84.c | 488 ++++++++++++++++++++++++++
> > > >  4 files changed, 514 insertions(+)
> > > >  create mode 100644 drivers/gpu/drm/bridge/ti-sn65dsi84.c
> > > >
> > > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > > index 12dd1fff2a39..44750ff7640c 100644
> > > > --- a/MAINTAINERS
> > > > +++ b/MAINTAINERS
> > > > @@ -5984,6 +5984,12 @@ S:       Maintained
> > > >  F:     Documentation/devicetree/bindings/display/ti/
> > > >  F:     drivers/gpu/drm/omapdrm/
> > > >
> > > > +DRM DRIVERS FOR TI SN65DSI84 DSI TO LVDS BRIDGE
> > > > +M:     Jagan Teki <jagan@amarulasolutions.com>
> > > > +S:     Maintained
> > > > +F:     Documentation/devicetree/bindings/display/bridge/ti,sn65dsi84.yaml
> > > > +F:     drivers/gpu/drm/bridge/ti-sn65dsi84.c
> > > > +
> > > >  DRM DRIVERS FOR V3D
> > > >  M:     Eric Anholt <eric@anholt.net>
> > > >  S:     Supported
> > > > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> > > > index e4110d6ca7b3..6494881bffb3 100644
> > > > --- a/drivers/gpu/drm/bridge/Kconfig
> > > > +++ b/drivers/gpu/drm/bridge/Kconfig
> > > > @@ -232,6 +232,25 @@ config DRM_TI_TFP410
> > > >         help
> > > >           Texas Instruments TFP410 DVI/HDMI Transmitter driver
> > > >
> > > > +config DRM_TI_SN65DSI84
> > > > +       tristate "TI SN65DSI84 DSI to LVDS bridge"
> > > > +       depends on OF
> > > > +       select DRM_KMS_HELPER
> > > > +       select REGMAP_I2C
> > > > +       select DRM_PANEL
> > > > +       select DRM_MIPI_DSI
> > > > +       help
> > > > +         Texas Instruments SN65DSI84 Single Channel DSI to Dual-link LVDS
> > > > +         bridge driver.
> > > > +
> > > > +         Bridge decodes MIPI DSI 18bpp RGB666 and 240bpp RG888 packets and
> > > > +         converts the formatted video data stream to a FlatLink compatible
> > > > +         LVDS output operating at pixel clocks operating from 25 MHx to
> > > > +         154 MHz.
> > > > +
> > > > +         SN65DSI84 offers a Dual-Link LVDS, Single-Link LVDS interface with
> > > > +         four data lanes per link.
> > > > +
> > > >  config DRM_TI_SN65DSI86
> > > >         tristate "TI SN65DSI86 DSI to eDP bridge"
> > > >         depends on OF
> > > > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> > > > index 86e7acc76f8d..3906052ef639 100644
> > > > --- a/drivers/gpu/drm/bridge/Makefile
> > > > +++ b/drivers/gpu/drm/bridge/Makefile
> > > > @@ -20,6 +20,7 @@ obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
> > > >  obj-$(CONFIG_DRM_TOSHIBA_TC358768) += tc358768.o
> > > >  obj-$(CONFIG_DRM_TOSHIBA_TC358775) += tc358775.o
> > > >  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
> > > > +obj-$(CONFIG_DRM_TI_SN65DSI84) += ti-sn65dsi84.o
> > > >  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
> > > >  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> > > >  obj-$(CONFIG_DRM_TI_TPD12S015) += ti-tpd12s015.o
> > > > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi84.c b/drivers/gpu/drm/bridge/ti-sn65dsi84.c
> > > > new file mode 100644
> > > > index 000000000000..3ed1f9a7d898
> > > > --- /dev/null
> > > > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi84.c
> > > > @@ -0,0 +1,488 @@
> > > > +// SPDX-License-Identifier: GPL-2.0
> > > > +/*
> > > > + * Copyright (c) 2021 Engicam srl
> > > > + * Copyright (C) 2021 Amarula Solutions(India)
> > > > + * Author: Jagan Teki <jagan@amarulasolutions.com>
> > > > + */
> > > > +
> > > > +#include <drm/drm_of.h>
> > > > +#include <drm/drm_panel.h>
> > > > +#include <drm/drm_print.h>
> > > > +#include <drm/drm_mipi_dsi.h>
> > > > +
> > > > +#include <linux/delay.h>
> > > > +#include <linux/gpio/consumer.h>
> > > > +#include <linux/i2c.h>
> > > > +#include <linux/module.h>
> > > > +#include <linux/regmap.h>
> > > > +
> > > > +/* sn65dsi84 registers */
> > > > +#define SN65DSI_SOFT_RESET             0x09
> > > > +#define SN65DSI_LVDS_CLK               0x0a
> > > > +#define SN65DSI_CLK_DIV                        0x0b
> > > > +#define SN65DSI_CLK_PLL                        0x0d
> > > > +#define SN65DSI_DSI_CFG                        0x10
> > > > +#define SN65DSI_DSI_CLK_EQ             0x11
> > > > +#define SN65DSI_DSI_CLK_RANGE          0x12
> > > > +#define SN65DSI_LVDS_MODE              0x18
> > > > +#define SN65DSI_CHA_LINE_LO            0x20
> > > > +#define SN65DSI_CHA_LINE_HI            0x21
> > > > +#define SN65DSI_CHA_VIRT_LO            0x24
> > > > +#define SN65DSI_CHA_VIRT_HI            0x25
> > > > +#define SN65DSI_CHA_SYNC_DELAY_LO      0x28
> > > > +#define SN65DSI_CHA_SYNC_DELAY_HI      0x29
> > > > +#define SN65DSI_CHA_HSYNC_WIDTH_LO     0x2c
> > > > +#define SN65DSI_CHA_HSYNC_WIDTH_HI     0x2d
> > > > +#define SN65DSI_CHA_VSYNC_WIDTH_LO     0x30
> > > > +#define SN65DSI_CHA_VSYNC_WIDTH_HI     0x31
> > > > +#define SN65DSI_CHA_HBACK_PORCH                0x34
> > > > +#define SN65DSI_CHA_VBACK_PORCH                0x36
> > > > +#define SN65DSI_CHA_HFRONT_PORCH       0x38
> > > > +#define SN65DSI_CHA_VFRONT_PORCH       0x3a
> > > > +#define SN65DSI_CHA_ERR                        0xe5
> > > > +
> > > > +/* sn65dsi register bits */
> > > > +#define SN65DSI_RESET_EN               BIT(0)
> > > > +#define SN65DSI_PLL_EN                 BIT(0)
> > > > +#define SN65DSI_LVDS_CLK_MASK          GENMASK(3, 1)
> > > > +#define SN65DSI_LVDS_CLK_SHIFT         1
> > > > +#define SN65DSI_LVDS_CLK_SRC_DSI       BIT(0)
> > > > +#define SN65DSI_CLK_DIV_MASK           GENMASK(7, 3)
> > > > +#define SN65DSI_CLK_DIV_SHIFT          3
> > > > +#define SN65DSI_DSI_LANE_MASK          GENMASK(4, 3)
> > > > +#define SN65DSI_DSI_LANE_SHIFT         3
> > > > +#define SN65DSI_LVDS_LINK_CFG          BIT(4)
> > > > +#define SN65DSI_LVDS_CHA_24BPP         BIT(3)
> > > > +#define SN65DSI_CHA_LOW_SYNC_DELAY     0x20
> > > > +#define SN65DSI_CHA_HIGH_SYNC_DELAY    0x00
> > > > +
> > > > +struct sn65dsi {
> > > > +       struct device                   *dev;
> > > > +       struct drm_bridge               bridge;
> > > > +       struct drm_bridge               *panel_bridge;
> > > > +
> > > > +       struct device_node              *host_node;
> > > > +       struct mipi_dsi_device          *dsi;
> > > > +       u8                              dsi_lanes;
> > > > +
> > > > +       struct regmap                   *regmap;
> > > > +       struct gpio_desc                *enable;
> > > > +};
> > > > +
> > > > +static const struct regmap_config sn65dsi_regmap_config = {
> > > > +       .reg_bits = 8,
> > > > +       .val_bits = 8,
> > > > +       .max_register = SN65DSI_CHA_ERR,
> > > > +       .name = "sn65dsi",
> > > > +       .cache_type = REGCACHE_RBTREE,
> > > > +};
> > > > +
> > > > +static inline struct sn65dsi *bridge_to_sn65dsi(struct drm_bridge *bridge)
> > > > +{
> > > > +       return container_of(bridge, struct sn65dsi, bridge);
> > > > +}
> > > > +
> > > > +static struct drm_display_mode *bridge_to_mode(struct drm_bridge *bridge)
> > > > +{
> > > > +       return &bridge->encoder->crtc->state->mode;
> > > > +}
> > > > +
> > > > +static void sn65dsi_setup_channels(struct sn65dsi *sn,
> > > > +                                  struct drm_display_mode *mode)
> > > > +{
> > > > +       u32 hsync_len, hfront_porch, hback_porch;
> > > > +       u32 vsync_len, vfront_porch, vback_porch;
> > > > +
> > > > +       hfront_porch = mode->hsync_start - mode->hdisplay;
> > > > +       hsync_len = mode->hsync_end - mode->hsync_start;
> > > > +       hback_porch = mode->htotal - mode->hsync_end;
> > > > +
> > > > +       vfront_porch = mode->vsync_start - mode->vdisplay;
> > > > +       vsync_len = mode->vsync_end - mode->vsync_start;
> > > > +       vback_porch = mode->vtotal - mode->vsync_end;
> > > > +
> > > > +       /* cha, lower 8-bits of hdisplay */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_LINE_LO, mode->hdisplay & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > >
> > > I don't find any reason for those msleep. I don't have on my setup
> > > with the same bridge
> >
> > As recommended by 8.2.2.1 Example Script from the datasheet.
> >
> > https://www.ti.com/product/SN65DSI84

That seems dodgy. A confirmation from TI as to whether those delays are
needed are not would be useful.

> Jurat wrap in one function and avoid, multiple msleep. Invesitgate
> even if delay_us in regamp can be
> used
> 
> > > > +       /* cha, upper 4-bits of hdisplay */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_LINE_HI, (mode->hdisplay >> 8) & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, lower 8-bits of vdisplay */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_VIRT_LO, mode->vdisplay & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, upper 4-bits of vdisplay */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_VIRT_HI, (mode->vdisplay >> 8) & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /*cha, lower sync delay */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_SYNC_DELAY_LO, SN65DSI_CHA_LOW_SYNC_DELAY);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /*cha, upper sync delay */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_SYNC_DELAY_HI, SN65DSI_CHA_HIGH_SYNC_DELAY);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, lower 8-bits of hsync_len */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_HSYNC_WIDTH_LO, hsync_len & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, upper 2-bits of hsync_len */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_HSYNC_WIDTH_HI, (hsync_len >> 8) & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, lower 8-bits of vsync_len */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_VSYNC_WIDTH_LO, vsync_len & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, upper 2-bits of vsync_len */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_VSYNC_WIDTH_HI, (vsync_len >> 8) & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, hback_porch */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_HBACK_PORCH, hback_porch & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, vback_porch */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_VBACK_PORCH, vback_porch & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, hfront_porch */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_HFRONT_PORCH, hfront_porch & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* cha, vfront_porch */
> > > > +       regmap_write(sn->regmap, SN65DSI_CHA_VFRONT_PORCH, vfront_porch & 0xff);
> > > > +
> > > > +       msleep(10);
> > > > +}
> > > > +
> > > > +static int sn65dsi_get_clk_range(int min, int max, unsigned long clock,
> > > > +                                unsigned long start, unsigned long diff)
> > > > +{
> > > > +       unsigned long next;
> > > > +       int i;
> > > > +
> > > > +       for (i = min; i <= max; i++) {
> > > > +               next = start + diff;
> > > > +               if (start <= clock && clock < next)
> > > > +                       return i;
> > > > +
> > > > +               start += diff;
> > > > +       }
> > > > +
> > > > +       return -EINVAL;
> > > > +}
> > > > +
> > > > +static void sn65dsi_enable(struct drm_bridge *bridge)
> > > > +{
> > > > +       struct sn65dsi *sn = bridge_to_sn65dsi(bridge);
> > > > +       struct drm_display_mode *mode = bridge_to_mode(bridge);
> > > > +       int bpp = mipi_dsi_pixel_format_to_bpp(sn->dsi->format);
> > > > +       unsigned int lanes = sn->dsi->lanes;
> > > > +       unsigned int pixel_clk = mode->clock * 1000;
> > > > +       unsigned int dsi_clk = pixel_clk * bpp / (lanes * 2);
> > > > +       unsigned int val;
> > > > +
> > > > +       /* set SOFT_RESET bit */
> > > > +       regmap_write(sn->regmap, SN65DSI_SOFT_RESET, SN65DSI_RESET_EN);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* set PLL_EN bit */
> > > > +       regmap_write(sn->regmap, SN65DSI_CLK_PLL, 0x0);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* setup lvds clock */
> > > > +       val = sn65dsi_get_clk_range(0, 5, pixel_clk, 25000000, 25000000);
> > > > +       if (val < 0) {
> > > > +               DRM_DEV_ERROR(sn->dev, "invalid LVDS clock range %d\n", val);
> > > > +               return;
> > > > +       }
> > > > +
> > > > +       regmap_update_bits(sn->regmap, SN65DSI_LVDS_CLK,
> > > > +                          SN65DSI_LVDS_CLK_MASK,
> > > > +                          val << SN65DSI_LVDS_CLK_SHIFT);
> > > > +
> > > > +       regmap_update_bits(sn->regmap, SN65DSI_LVDS_CLK,
> > > > +                          SN65DSI_LVDS_CLK_SRC_DSI,
> > > > +                          SN65DSI_LVDS_CLK_SRC_DSI);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* setup bridge clock divider */
> > > > +       val = (dsi_clk / pixel_clk) - 1;
> > > > +       regmap_update_bits(sn->regmap, SN65DSI_CLK_DIV,
> > > > +                          SN65DSI_CLK_DIV_MASK,
> > > > +                          val << SN65DSI_CLK_DIV_SHIFT);
> > > > +       msleep(10);
> > > > +
> > > > +       /* configure dsi */
> > > > +       regmap_update_bits(sn->regmap, SN65DSI_DSI_CFG,
> > > > +                          SN65DSI_DSI_LANE_MASK,
> > > > +                          lanes << SN65DSI_DSI_LANE_SHIFT);
> > > > +       msleep(10);
> > > > +
> > >
> > > Most of those, look like. I don't know why it does not work without.
> > > Where is mention in datasheet?
> > >
> > > > +       /* dsi clock range */
> > > > +       val = sn65dsi_get_clk_range(8, 100, dsi_clk, 40000000, 5000000);
> > > > +       if (val < 0) {
> > > > +               DRM_DEV_ERROR(sn->dev, "invalid DSI clock range %d\n", val);
> > > > +               return;
> > > > +       }
> > > > +
> > > > +       regmap_write(sn->regmap, SN65DSI_DSI_CLK_RANGE, val);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* setup lvds channels */
> > > > +       regmap_read(sn->regmap, SN65DSI_LVDS_MODE, &val);
> > > > +       if (bpp == 24)
> > > > +               val |= SN65DSI_LVDS_CHA_24BPP;
> > > > +       regmap_write(sn->regmap, SN65DSI_LVDS_MODE, val);
> > > > +
> > > > +       msleep(10);
> > > > +
> > > > +       /* TODO Channel B required to set up for dual-link LVDS */
> > > > +       sn65dsi_setup_channels(sn, mode);
> > > > +
> > >
> > > If you are supporting 84 this code can be drop.
> >
> > Right now the above function is setting up channel A for single-link
> > LVDS. 84 support Single and Dual link LVDS.

-- 
Regards,

Laurent Pinchart