linux-kernel - Re: [PATCH v2 2/5] drm: bridge: dw_hdmi: default enable workaround to clear the overflow

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Date:   Sun, 10 Apr 2022 12:20:59 +0200
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        andrzej.hajda@...el.com, narmstrong@...libre.com,
        robert.foss@...aro.org, Laurent.pinchart@...asonboard.com,
        jonas@...boo.se, hverkuil-cisco@...all.nl,
        Sandor Yu <Sandor.yu@....com>
Cc:     Sandor.yu@....com, shengjiu.wang@....com, cai.huoqing@...ux.dev,
        maxime@...no.tech, harry.wentland@....com
Subject: Re: [PATCH v2 2/5] drm: bridge: dw_hdmi: default enable workaround to clear the overflow

Dne petek, 08. april 2022 ob 12:32:25 CEST je Sandor Yu napisal(a):
> i.MX8MPlus (v2.13a) has verified need the workaround to clear the
> overflow with one iteration.
> Only i.MX6Q(v1.30a) need the workaround with 4 iterations,
> the others versions later than v1.3a have been identified as needing
> the workaround with a single iteration.
> 
> Default enable the workaround with one iteration for all versions
> later than v1.30a.
> 
> Signed-off-by: Sandor Yu <Sandor.yu@....com>
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 23 +++++++----------------
>  1 file changed, 7 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index
> 4befc104d220..02d8f7e08814 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -2086,30 +2086,21 @@ static void dw_hdmi_clear_overflow(struct dw_hdmi
> *hdmi) * then write one of the FC registers several times.
>  	 *
>  	 * The number of iterations matters and depends on the HDMI TX 
revision
> -	 * (and possibly on the platform). So far i.MX6Q (v1.30a), i.MX6DL
> -	 * (v1.31a) and multiple Allwinner SoCs (v1.32a) have been 
identified
> -	 * as needing the workaround, with 4 iterations for v1.30a and 1
> -	 * iteration for others.
> -	 * The Amlogic Meson GX SoCs (v2.01a) have been identified as 
needing
> -	 * the workaround with a single iteration.
> -	 * The Rockchip RK3288 SoC (v2.00a) and RK3328/RK3399 SoCs 
(v2.11a) have
> -	 * been identified as needing the workaround with a single 
iteration.
> +	 * (and possibly on the platform).
> +	 * 4 iterations for i.MX6Q(v1.30a) and 1 iteration for others.
> +	 * i.MX6DL (v1.31a), Allwinner SoCs (v1.32a), Rockchip RK3288 SoC
> (v2.00a), +	 * Amlogic Meson GX SoCs (v2.01a), RK3328/RK3399 SoCs (v2.11a)
> +	 * and i.MX8MPlus (v2.13a) have been identified as needing the 
workaround
> +	 * with a single iteration.
>  	 */

It would be easier to read and modify later if platforms/controllers/variants 
are given as list, one per line, but it could be done later.

Best regards,
Jernej

> 
>  	switch (hdmi->version) {
>  	case 0x130a:
>  		count = 4;
>  		break;
> -	case 0x131a:
> -	case 0x132a:
> -	case 0x200a:
> -	case 0x201a:
> -	case 0x211a:
> -	case 0x212a:
> +	default:
>  		count = 1;
>  		break;
> -	default:
> -		return;
>  	}
> 
>  	/* TMDS software reset */