linux-kernel - Re: [RFC PATCH 2/2] drm/etnaviv: add clock gating workaround for GC7000 r6202

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Message-ID: <df3c79738d997ace50bac2433a988f3914739cf6.camel@pengutronix.de>
Date:   Tue, 15 Jun 2021 09:47:48 +0200
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Michael Walle <michael@...le.cc>, etnaviv@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Russell King <linux+etnaviv@...linux.org.uk>,
        Christian Gmeiner <christian.gmeiner@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [RFC PATCH 2/2] drm/etnaviv: add clock gating workaround for
 GC7000 r6202

Hi Michael,

Am Dienstag, dem 15.06.2021 um 00:17 +0200 schrieb Michael Walle:
> The LS1028A SoC errata sheet mentions A-050121 "GPU hangs if clock
> gating for Rasterizer, Setup Engine and Texture Engine are enabled".
> The workaround is to disable the corresponding clock gatings.
> 
> Signed-off-by: Michael Walle <michael@...le.cc>
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> index 4102bcea3341..574e4e04dddc 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> @@ -613,6 +613,12 @@ static void etnaviv_gpu_enable_mlcg(struct etnaviv_gpu *gpu)
>  	    etnaviv_is_model_rev(gpu, GC2000, 0x5108))
>  		pmc |= VIVS_PM_MODULE_CONTROLS_DISABLE_MODULE_CLOCK_GATING_TX;
>  
> +	/* Disable RS, SE, TE clock gating on affected core revisions. */

This comment is wrong. RS (resolver) is a different engine than RA
(rasterizer) and the texture engine is abbreviated TX throughout the
driver.

Regards,
Lucas

> +	if (etnaviv_is_model_rev(gpu, GC7000, 0x6202))
> +		pmc |= VIVS_PM_MODULE_CONTROLS_DISABLE_MODULE_CLOCK_GATING_SE |
> +		       VIVS_PM_MODULE_CONTROLS_DISABLE_MODULE_CLOCK_GATING_RA |
> +		       VIVS_PM_MODULE_CONTROLS_DISABLE_MODULE_CLOCK_GATING_TX;
> +
>  	pmc |= VIVS_PM_MODULE_CONTROLS_DISABLE_MODULE_CLOCK_GATING_RA_HZ;
>  	pmc |= VIVS_PM_MODULE_CONTROLS_DISABLE_MODULE_CLOCK_GATING_RA_EZ;
>