[PATCH][RESEND] drm/bridge: ti-sn65dsi83: Check link status register after enabling the bridge

[Laurent Pinchart]

Hi Marek,

Thank you for the patch.

On Sun, Feb 13, 2022 at 03:26:48AM +0100, Marek Vasut wrote:
> In rare cases, the bridge may not start up correctly, which usually
> leads to no display output. In case this happens, warn about it in
> the kernel log.

Do you know what this is caused by ? It's a bit annoying to add a 10+ms
delay at start time just to be notified of rare cases.

> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Jagan Teki <jagan at amarulasolutions.com>
> Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Cc: Linus Walleij <linus.walleij at linaro.org>
> Cc: Robert Foss <robert.foss at linaro.org>
> Cc: Sam Ravnborg <sam at ravnborg.org>
> Cc: dri-devel at lists.freedesktop.org
> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi83.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index 19daaddd29a41..1d7c154ea1d79 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> @@ -488,6 +488,11 @@ static void sn65dsi83_atomic_enable(struct drm_bridge *bridge,
>  	/* Clear all errors that got asserted during initialization. */
>  	regmap_read(ctx->regmap, REG_IRQ_STAT, &pval);
>  	regmap_write(ctx->regmap, REG_IRQ_STAT, pval);
> +
> +	usleep_range(10000, 12000);
> +	regmap_read(ctx->regmap, REG_IRQ_STAT, &pval);
> +	if (pval)
> +		dev_err(ctx->dev, "Unexpected link status 0x%02x\n", pval);
>  }
>  
>  static void sn65dsi83_atomic_disable(struct drm_bridge *bridge,

-- 
Regards,

Laurent Pinchart