linux-kernel - Re: [PATCH 11/12] drm/nouveau: support GK20A in nouveau_accel

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Message-ID: <20140324231014.GI17218@mithrandir>
Date:	Tue, 25 Mar 2014 00:10:16 +0100
From:	Thierry Reding <thierry.reding@...il.com>
To:	Alexandre Courbot <acourbot@...dia.com>
Cc:	Ben Skeggs <bskeggs@...hat.com>, nouveau@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org, linux-tegra@...r.kernel.org,
	linux-kernel@...r.kernel.org, gnurou@...il.com
Subject: Re: [PATCH 11/12] drm/nouveau: support GK20A in nouveau_accel_init()

On Mon, Mar 24, 2014 at 05:42:33PM +0900, Alexandre Courbot wrote:
> GK20A does not embed a dedicated COPY engine and thus cannot allocate
> the copy channel that nouveau_accel_init() attempts to create. It also
> lacks any display hardware, so the creation of a software channel does
> not apply neither.

Perhaps this should be two separate patches?

> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
[...]
> +	if (device->chipset == 0xea) {
> +		/* gk20a does not have CE0/CE1 */

This would be another good candidate for a feature flag.

> +		arg0 = NVE0_CHANNEL_IND_ENGINE_GR;
> +		arg1 = 1;
> +	} else
>  	if (device->card_type >= NV_E0) {

The formatting here is somewhat weird. From a brief look I couldn't find
any indication that nouveau deviates from the standard coding style, so
this should be:

	} else if (...) {

> +	/* Need to figure out how to handle sw for gk20a */
> +	if (device->chipset == 0xea)
> +		goto skip_sw_init;

The commit message makes it sound like SW isn't needed since gk20a
"lacks any display hardware". In that case the comment here doesn't make
much sense.

Thierry

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