Message-ID: <20200908175707.GH11405@pendragon.ideasonboard.com>
Date:   Tue, 8 Sep 2020 20:57:07 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Vinay Simha B N <simhavcs@...il.com>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/bridge/tc358775: Fixes bus formats read

Hi Vinay,

On Tue, Sep 08, 2020 at 11:22:48PM +0530, Vinay Simha B N wrote:
> laurent,
> 
> Please review or give some feedback.

I'm sorry, I have very little time these days :-( Maybe Neil can provide
feedback ?

> On Tue, Aug 25, 2020 at 7:57 PM Vinay Simha B N <simhavcs@...il.com> wrote:
> 
> > laurent,
> >
> > Please review or give some feedback.
> >
> > On Thu, Aug 13, 2020 at 9:09 PM Vinay Simha B N <simhavcs@...il.com>
> > wrote:
> > >
> > > laurent,
> > >
> > > The code sequence was a problem. *num_inputs_fmts =
> > > ARRAY_SIZE(tc_lvds_in_bus_fmts); should come first and then allocate
> > > the kcalloc.
> > >
> > > input_fmts = kcalloc(*num_input_fmts, ARRAY_SIZE(tc_lvds_in_bus_fmts),
> > >                              GFP_KERNEL);
> > > ..
> > >         for (i = 0; i < ARRAY_SIZE(tc_lvds_in_bus_fmts); ++i)
> > >                 input_fmts[i] = tc_lvds_in_bus_fmts[i];
> > >
> > >         *num_inputs_fmts = ARRAY_SIZE(tc_lvds_in_bus_fmts);
> > >
> > > So, internally in the drm pipeline get set the input format based on
> > > the output formats?
> > >
> > > On Wed, Aug 12, 2020 at 10:45 PM Vinay Simha B N <simhavcs@...il.com>
> > wrote:
> > > >
> > > > laurent,
> > > >
> > > > if i add the .atomic_get_input_bus_fmts =
> > > > tc_bridge_get_input_bus_fmts, with the implementation suggested,
> > > > system does not boot fully, the reason is, we capture all the
> > > > supported input formats, but not sure where to set the final input
> > > > format. Please suggest.
> > > >
> > > > for (i = 0; i < ARRAY_SIZE(tc_lvds_in_bus_fmts); ++i)
> > > >                 input_fmts[i] = tc_lvds_in_bus_fmts[i];
> > > >
> > > >         *num_input_fmts = ARRAY_SIZE(tc_lvds_in_bus_fmts);
> > > >
> > > > On Wed, Aug 12, 2020 at 8:25 PM Vinay Simha B N <simhavcs@...il.com>
> > wrote:
> > > > >
> > > > > laurent,
> > > > >
> > > > > Video data input format :  RGB666 loosely packed 24 bits per pixel
> > > > > Can we use MEDIA_BUS_FMT_RGB666_1X24_CPADHI? There was no information
> > > > > wrt CPADHI or for loosely packed
> > > > >
> > > > > static const u32 tc_lvds_in_bus_fmts[] = {
> > > > >         MEDIA_BUS_FMT_RGB565_1X16,
> > > > >         MEDIA_BUS_FMT_RGB666_1X18,
> > > > >         MEDIA_BUS_FMT_RGB666_1X24_CPADHI,
> > > > >         MEDIA_BUS_FMT_RBG888_1X24,
> > > > > };
> > > > >
> > > > > for (i = 0; i < ARRAY_SIZE(tc_lvds_in_bus_fmts); ++i)
> > > > >                 input_fmts[i] = tc_lvds_in_bus_fmts[i];
> > > > > >> This will have all the available input formats, but finally which
> > video data input format chosen?
> > > > > Since dsi->format = MIPI_DSI_FMT_RGB888 is used does it chooses
> > > > > MEDIA_BUS_FMT_RBG888_1X24 by the drm pipeline
> > > > >
> > > > > On Wed, Aug 12, 2020 at 6:48 PM Laurent Pinchart
> > > > > <laurent.pinchart@...asonboard.com> wrote:
> > > > > >
> > > > > > Hi Vinay,
> > > > > >
> > > > > > On Wed, Aug 12, 2020 at 06:07:52PM +0530, Vinay Simha B N wrote:
> > > > > > > On Wed, Aug 12, 2020 at 3:24 PM Laurent Pinchart wrote:
> > > > > > > > On Wed, Aug 12, 2020 at 12:55:50PM +0530, Vinay Simha BN wrote:
> > > > > > > > > - bus formats read from
> > drm_bridge_state.output_bus_cfg.format
> > > > > > > > >   and .atomic_get_input_bus_fmts() instead of connector
> > > > > > > > >
> > > > > > > > > Signed-off-by: Vinay Simha BN <simhavcs@...il.com>
> > > > > > > > >
> > > > > > > > > ---
> > > > > > > > >  v1:
> > > > > > > > >  * Laurent Pinchart review comments incorporated
> > > > > > > > >    drm_bridge_state.output_bus_cfg.format
> > > > > > > > >    instead of connector
> > > > > > > > > ---
> > > > > > > > >  drivers/gpu/drm/bridge/tc358775.c | 76
> > ++++++++++++++++++++++++++++++---------
> > > > > > > > >  1 file changed, 59 insertions(+), 17 deletions(-)
> > > > > > > > >
> > > > > > > > > diff --git a/drivers/gpu/drm/bridge/tc358775.c
> > b/drivers/gpu/drm/bridge/tc358775.c
> > > > > > > > > index 7da15cd..5d8714a 100644
> > > > > > > > > --- a/drivers/gpu/drm/bridge/tc358775.c
> > > > > > > > > +++ b/drivers/gpu/drm/bridge/tc358775.c
> > > > > > > > > @@ -271,6 +271,13 @@ struct tc_data {
> > > > > > > > >       struct gpio_desc        *stby_gpio;
> > > > > > > > >       u8                      lvds_link; /* single-link or
> > dual-link */
> > > > > > > > >       u8                      bpc;
> > > > > > > > > +     u32                     output_bus_fmt;
> > > > > > > > > +};
> > > > > > > > > +
> > > > > > > > > +static const u32 tc_lvds_out_bus_fmts[] = {
> > > > > > > > > +     MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,
> > > > > > > > > +     MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,
> > > > > > > > > +     MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> > > > > > > > >  };
> > > > > > > > >
> > > > > > > > >  static inline struct tc_data *bridge_to_tc(struct
> > drm_bridge *b)
> > > > > > > > > @@ -359,19 +366,6 @@ static void d2l_write(struct i2c_client
> > *i2c, u16 addr, u32 val)
> > > > > > > > >                       ret, addr);
> > > > > > > > >  }
> > > > > > > > >
> > > > > > > > > -/* helper function to access bus_formats */
> > > > > > > > > -static struct drm_connector *get_connector(struct
> > drm_encoder *encoder)
> > > > > > > > > -{
> > > > > > > > > -     struct drm_device *dev = encoder->dev;
> > > > > > > > > -     struct drm_connector *connector;
> > > > > > > > > -
> > > > > > > > > -     list_for_each_entry(connector,
> > &dev->mode_config.connector_list, head)
> > > > > > > > > -             if (connector->encoder == encoder)
> > > > > > > > > -                     return connector;
> > > > > > > > > -
> > > > > > > > > -     return NULL;
> > > > > > > > > -}
> > > > > > > > > -
> > > > > > > > >  static void tc_bridge_enable(struct drm_bridge *bridge)
> > > > > > > > >  {
> > > > > > > > >       struct tc_data *tc = bridge_to_tc(bridge);
> > > > > > > > > @@ -380,7 +374,6 @@ static void tc_bridge_enable(struct
> > drm_bridge *bridge)
> > > > > > > > >       u32 val = 0;
> > > > > > > > >       u16 dsiclk, clkdiv, byteclk, t1, t2, t3, vsdelay;
> > > > > > > > >       struct drm_display_mode *mode;
> > > > > > > > > -     struct drm_connector *connector =
> > get_connector(bridge->encoder);
> > > > > > > > >
> > > > > > > > >       mode = &bridge->encoder->crtc->state->adjusted_mode;
> > > > > > > > >
> > > > > > > > > @@ -451,14 +444,13 @@ static void tc_bridge_enable(struct
> > drm_bridge *bridge)
> > > > > > > > >       d2l_write(tc->i2c, LVPHY0, LV_PHY0_PRBS_ON(4) |
> > LV_PHY0_ND(6));
> > > > > > > > >
> > > > > > > > >       dev_dbg(tc->dev, "bus_formats %04x bpc %d\n",
> > > > > > > > > -             connector->display_info.bus_formats[0],
> > > > > > > > > +             tc->output_bus_fmt,
> > > > > > > > >               tc->bpc);
> > > > > > > > >       /*
> > > > > > > > >        * Default hardware register settings of tc358775
> > configured
> > > > > > > > >        * with MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA jeida-24
> > format
> > > > > > > > >        */
> > > > > > > > > -     if (connector->display_info.bus_formats[0] ==
> > > > > > > > > -             MEDIA_BUS_FMT_RGB888_1X7X4_SPWG) {
> > > > > > > > > +     if (tc->output_bus_fmt ==
> > MEDIA_BUS_FMT_RGB888_1X7X4_SPWG) {
> > > > > > > > >               /* VESA-24 */
> > > > > > > > >               d2l_write(tc->i2c, LV_MX0003, LV_MX(LVI_R0,
> > LVI_R1, LVI_R2, LVI_R3));
> > > > > > > > >               d2l_write(tc->i2c, LV_MX0407, LV_MX(LVI_R4,
> > LVI_R7, LVI_R5, LVI_G0));
> > > > > > > > > @@ -590,6 +582,51 @@ static int tc358775_parse_dt(struct
> > device_node *np, struct tc_data *tc)
> > > > > > > > >       return 0;
> > > > > > > > >  }
> > > > > > > > >
> > > > > > > > > +static int tc_bridge_atomic_check(struct drm_bridge *bridge,
> > > > > > > > > +                               struct drm_bridge_state
> > *bridge_state,
> > > > > > > > > +                               struct drm_crtc_state
> > *crtc_state,
> > > > > > > > > +                               struct drm_connector_state
> > *conn_state)
> > > > > > > > > +{
> > > > > > > > > +     struct tc_data *tc = bridge_to_tc(bridge);
> > > > > > > > > +
> > > > > > > > > +     tc->output_bus_fmt =
> > bridge_state->output_bus_cfg.format;
> > > > > > > >
> > > > > > > > .atomic_check() isn't allowed to modify the device state,
> > neither the
> > > > > > > > hardware state nor the software state in drm_bridge or
> > tc_data. You can
> > > > > > > > instead access the bridge state directly in
> > tc_bridge_enable(), with
> > > > > > > >
> > > > > > > >         struct drm_bridge_state *state =
> > > > > > > >                 drm_priv_to_bridge_state(bridge->base.state);
> > > > > > >
> > > > > > > Currently the driver is picking up from the dts panel
> > > > > > > (data-mapping = "vesa-24";) or jeida-24 or jeida-18.
> > > > > > >
> > > > > > > Does state->output_bus_cfg.format  get set from the data-mapping?
> > > > > >
> > > > > > It should. The drm_panel should take care of that. In
> > > > > > panel_simple_get_non_edid_modes(), it calls
> > > > > >
> > > > > >         if (panel->desc->bus_format)
> > > > > >
> >  drm_display_info_set_bus_formats(&connector->display_info,
> > > > > >
> > &panel->desc->bus_format, 1);
> > > > > >
> > > > > > to initialize the bus format in display_info. Then, the DRM bridge
> > > > > > helper drm_atomic_bridge_chain_select_bus_fmts() retrieves the
> > output
> > > > > > format by calling .atomic_get_output_bus_fmts() if implemented by
> > the
> > > > > > last bridge in the chain, or directly from the connector
> > display_info.
> > > > > > The last bridge in the chain is a DRM panel bridge, and doesn't
> > > > > > implement .atomic_get_output_bus_fmts(), so the format from
> > display_info
> > > > > > is used, and is stored in the output_bus_cfg.format field of this
> > bridge
> > > > > > in select_bus_fmt_recursive().
> > > > > >
> > > > > > If something doesn't work according to the plan, I can help you
> > > > > > debugging.
> > > > > >
> > > > > > > > > +
> > > > > > > > > +     dev_dbg(tc->dev, "output_bus_fmt %04x\n",
> > tc->output_bus_fmt);
> > > > > > > > > +
> > > > > > > > > +     return 0;
> > > > > > > > > +}
> > > > > > > > > +
> > > > > > > > > +static u32 *
> > > > > > > > > +tc_bridge_get_input_bus_fmts(struct drm_bridge *bridge,
> > > > > > > > > +                          struct drm_bridge_state
> > *bridge_state,
> > > > > > > > > +                          struct drm_crtc_state *crtc_state,
> > > > > > > > > +                          struct drm_connector_state
> > *conn_state,
> > > > > > > > > +                          u32 output_fmt,
> > > > > > > > > +                          unsigned int *num_input_fmts)
> > > > > > > > > +{
> > > > > > > > > +     u32 *input_fmts = NULL;
> > > > > > > > > +     int i;
> > > > > > > >
> > > > > > > > i only takes positive values, so it can be an unsigned int.
> > > > > > > >
> > > > > > > > > +
> > > > > > > > > +     *num_input_fmts = 0;
> > > > > > > > > +
> > > > > > > > > +     for (i = 0 ; i < ARRAY_SIZE(tc_lvds_out_bus_fmts) ;
> > ++i) {
> > > > > > > > > +             if (output_fmt == tc_lvds_out_bus_fmts[i]) {
> > > > > > > > > +                     *num_input_fmts = 1;
> > > > > > > > > +                     input_fmts = kcalloc(*num_input_fmts,
> > > > > > > > > +
> > sizeof(*input_fmts),
> > > > > > > > > +                                          GFP_KERNEL);
> > > > > > > > > +                     if (!input_fmts)
> > > > > > > > > +                             return NULL;
> > > > > > > > > +
> > > > > > > > > +                     input_fmts[0] = output_fmt;
> > > > > > > >
> > > > > > > > I don't think this is right, the input of the bridge isn't
> > LVDS, is it ?
> > > > > > >
> > > > > > > Input to the bridge is DSI, format is already set
> > > > > > >
> > > > > > > dsi->format = MIPI_DSI_FMT_RGB888;
> > > > > > >
> > > > > > > enum mipi_dsi_pixel_format {
> > > > > > >         MIPI_DSI_FMT_RGB888,
> > > > > > >         MIPI_DSI_FMT_RGB666,
> > > > > > >         MIPI_DSI_FMT_RGB666_PACKED,
> > > > > > >         MIPI_DSI_FMT_RGB565,
> > > > > > > };
> > > > > > > include/drm/drm_mipi_dsi.h
> > > > > > >
> > > > > > > Why do we require this atomic_get_input_bus_fmts?
> > > > > > >
> > > > > > > Do i need to implement both atomic_get_input_bus_fmts and
> > > > > > > atomic_get_output_bus_fmts?
> > > > > >
> > > > > > .atomic_get_output_bus_fmts() is only need for the last bridge in
> > the
> > > > > > chain, and is not mandatory when that bridge supports a single
> > format.
> > > > > > As this bridge can't be last (if the output is connect to a panel,
> > there
> > > > > > will be a drm_bridge wrapping the drm_panel), you don't have to
> > > > > > implement that operation.
> > > > > >
> > > > > > .atomic_get_input_bus_fmts() is used to negotiate formats along the
> > > > > > pipeline. The helps the DRM bridge helpers figure out what formats
> > are
> > > > > > possible, with the help of bridges that must report what input
> > formats
> > > > > > are compatible with a given output format. The DRM bridge helpers
> > will
> > > > > > take care of the rest.
> > > > > >
> > > > > > So, for this bridge, the input and output formats are decoupled.
> > The
> > > > > > bridge can output any of the three supported LVDS formats,
> > regardless of
> > > > > > what format it gets at its input. You should thus verify that the
> > output
> > > > > > format you receive in this function is supported (and return NULL
> > if it
> > > > > > isn't), and then return the list of supported input formats. If you
> > > > > > don't implement .atomic_get_input_bus_fmts(), then the DRM bridge
> > > > > > helpers will consider that the input and output formats are the
> > same,
> > > > > > and will set the output format of the previous bridge to, for
> > example,
> > > > > > MEDIA_BUS_FMT_RGB666_1X7X3_SPWG. It may work if the previous bridge
> > > > > > doesn't care about its output format, but if it does, then it will
> > be
> > > > > > puzzled, as the previous bridge outputs DSI, not LVDS.
> > > > > >
> > > > > > > > As far as I can tell, the hardware support transcoding any of
> > the
> > > > > > > > supported input formats (RGB565, RGB666 or RGB888) to any of
> > the
> > > > > > > > supported output formats. How about the following ?
> > > > > > > >
> > > > > > > > static const u32 tc_lvds_in_bus_fmts[] = {
> > > > > > > >         MEDIA_BUS_FMT_RGB565_1X16,
> > > > > > > >         MEDIA_BUS_FMT_RGB666_1X18,
> > > > > > > >         MEDIA_BUS_FMT_RBG888_1X24,
> > > > > > > > };
> > > > > > > >
> > > > > > > > ...
> > > > > > > >
> > > > > > > >         u32 *input_fmts;
> > > > > > > >         unsigned int i;
> > > > > > > >
> > > > > > > >         *num_input_fmts = 0;
> > > > > > > >
> > > > > > > >         for (i = 0 ; i < ARRAY_SIZE(tc_lvds_out_bus_fmts) ;
> > ++i) {
> > > > > > > >                 if (output_fmt == tc_lvds_out_bus_fmts[i])
> > > > > > > >                         break;
> > > > > > > >         }
> > > > > > > >
> > > > > > > >         if (i == ARRAY_SIZE(tc_lvds_out_bus_fmts))
> > > > > > > >                 return NULL;
> > > > > > > >
> > > > > > > >         input_fmts = kcalloc(*num_input_fmts,
> > ARRAY_SIZE(tc_lvds_in_bus_fmts),
> > > > > > > >                              GFP_KERNEL);
> > > > > > > >         if (!input_fmts)
> > > > > > > >                 return NULL;
> > > > > > > >
> > > > > > > >         for (i = 0; i < ARRAY_SIZE(tc_lvds_in_bus_fmts); ++i)
> > > > > > > >                 input_fmts[i] = tc_lvds_in_bus_fmts[i];
> > > > > > > >
> > > > > > > >         *num_inputs_fmts = ARRAY_SIZE(tc_lvds_in_bus_fmts);
> > > > > > > >         return input_fmts;
> > > > > > > >
> > > > > > > > > +
> > > > > > > > > +                     break;
> > > > > > > > > +             }
> > > > > > > > > +     }
> > > > > > > > > +
> > > > > > > > > +     return input_fmts;
> > > > > > > > > +}
> > > > > > > > > +
> > > > > > > > >  static int tc_bridge_attach(struct drm_bridge *bridge,
> > > > > > > > >                           enum drm_bridge_attach_flags flags)
> > > > > > > > >  {
> > > > > > > > > @@ -639,6 +676,11 @@ static int tc_bridge_attach(struct
> > drm_bridge *bridge,
> > > > > > > > >  }
> > > > > > > > >
> > > > > > > > >  static const struct drm_bridge_funcs tc_bridge_funcs = {
> > > > > > > > > +     .atomic_duplicate_state =
> > drm_atomic_helper_bridge_duplicate_state,
> > > > > > > > > +     .atomic_destroy_state =
> > drm_atomic_helper_bridge_destroy_state,
> > > > > > > > > +     .atomic_reset = drm_atomic_helper_bridge_reset,
> > > > > > > > > +     .atomic_get_input_bus_fmts =
> > tc_bridge_get_input_bus_fmts,
> > > > > > > > > +     .atomic_check = tc_bridge_atomic_check,
> > > > > > > > >       .attach = tc_bridge_attach,
> > > > > > > > >       .pre_enable = tc_bridge_pre_enable,
> > > > > > > > >       .enable = tc_bridge_enable,

-- 
Regards,

Laurent Pinchart

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