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SubjectRe: [PATCH] drm/bridge/tc358775: Fixes bus formats read
laurent,

please see the reply inline below.

On Wed, Aug 12, 2020 at 3:24 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Vinay,
>
> Thank you for the patch.
>
> 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@gmail.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?

> > +
> > + 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?

> 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



--
regards,
vinaysimha

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