Re: [PATCH RESEND v2] drm/bridge/tc358775: Fixes bus formats read

[Laurent Pinchart]

Hi Vinay,

Thank you for the patch.

I'm afraid I've had close to no time for DRM bridge maintenance over the
past few months, and I don't expect the situation to improve soon.  I
know how painful it can be to keep pinging without receiving any reply.
I'm sorry about that, we have a shortage of maintainers for this part of
the subsystem and it seems difficult to recruit.

On Thu, Oct 22, 2020 at 12:15:47PM +0530, Vinay Simha BN wrote:
> - atomic_check removed
> - video data input and output formats added
> - 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@xxxxxxxxx>
> 
> ---
> v1:
>  * Laurent Pinchart review comments incorporated
>    drm_bridge_state.output_bus_cfg.format
>    instead of connector
> v2:
>  * Laurent Pinchart review comments incorporated
>    atomic_check removed
>    video data input and output formats added
> ---
>  drivers/gpu/drm/bridge/tc358775.c | 75 ++++++++++++++++++++++++++++++---------
>  1 file changed, 58 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/tc358775.c b/drivers/gpu/drm/bridge/tc358775.c
> index 2272adc..cc27570 100644
> --- a/drivers/gpu/drm/bridge/tc358775.c
> +++ b/drivers/gpu/drm/bridge/tc358775.c
> @@ -271,6 +271,20 @@ 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_in_bus_fmts[] = {
> +	MEDIA_BUS_FMT_RGB565_1X16,
> +	MEDIA_BUS_FMT_RGB666_1X18,
> +	MEDIA_BUS_FMT_RGB666_1X24_CPADHI,
> +	MEDIA_BUS_FMT_RBG888_1X24,
> +};
> +
> +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 +373,6 @@ 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 +381,10 @@ 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);
> +	struct drm_bridge_state *state =
> +			drm_priv_to_bridge_state(bridge->base.state);
> +
> +	tc->output_bus_fmt = state->output_bus_cfg.format;
>  
>  	mode = &bridge->encoder->crtc->state->adjusted_mode;
>  
> @@ -451,14 +455,13 @@ 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) {

As output_bus_fmt is only used in this function, I would make this a
local variable and drop the output_bus_fmt field from tc_data. You could
even use state->output_bus_cfg.format directly in the two locations
where the value is needed without a local variable, up to you.

>  		/* 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 +593,40 @@ static int tc358775_parse_dt(struct device_node *np, struct tc_data *tc)
>  	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;
> +	u8 i;

You can make this an unsigned int, a u8 won't save space of CPU time.

> +
> +	*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;
> +
> +	*num_input_fmts = ARRAY_SIZE(tc_lvds_in_bus_fmts);
> +
> +	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];

This could be written

	memcpy(input_fmts, tc_lvds_in_bus_fmts, sizeof(input_fmts));

With those small changes,

Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

> +
> +	return input_fmts;
> +}
> +
>  static int tc_bridge_attach(struct drm_bridge *bridge,
>  			    enum drm_bridge_attach_flags flags)
>  {
> @@ -639,6 +676,10 @@ 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,
>  	.attach = tc_bridge_attach,
>  	.pre_enable = tc_bridge_pre_enable,
>  	.enable = tc_bridge_enable,

-- 
Regards,

Laurent Pinchart