linux-kernel - Re: [PATCH 0/2] firmware: cs_dsp: Remove usage of GFP

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Message-ID: <20250213161059-a4c53711-fdf6-480c-af49-f9f36227ba42@linutronix.de>
Date: Thu, 13 Feb 2025 16:16:25 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Mark Brown <broonie@...nel.org>
Cc: Richard Fitzgerald <rf@...nsource.cirrus.com>, 
	Simon Trimmer <simont@...nsource.cirrus.com>, Charles Keepax <ckeepax@...nsource.cirrus.com>, 
	patches@...nsource.cirrus.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] firmware: cs_dsp: Remove usage of GFP_DMA

On Thu, Feb 13, 2025 at 03:06:59PM +0000, Mark Brown wrote:
> On Thu, Feb 13, 2025 at 02:28:06PM +0000, Richard Fitzgerald wrote:
> > On 11/02/2025 5:21 pm, Richard Fitzgerald wrote:
> 
> > > > Not tested on real hardware.
> > > > This came up while porting kunit to mips64.
> > > > Apparently GFP_DMA does not work there, but IMO the usage of GFP_DMA by
> 
> > I would say that is a bug in mips64 that should be fixed in mips64.
> > It is not reasonable to expect generic drivers to have special cases for
> > platforms that don't handle GFP_DMA.

Indeed, I did that, too.

> What specifically is the issue?  If it's a build time issue I'd
> definitely agree that we should just be able to assume that platforms at
> least build.  IIRC there is a Kconfig you can depend on for DMA but it
> seems more trouble than it's worth to fix all users.

More details in [0], It's only a runtime issue.

I'm still wondering how all the on-stack buffers used with regmap_raw_read()
and regmap_raw_write() by cs_dsp are satisfying the DMA requirements.

[0] https://lore.kernel.org/lkml/20250212-kunit-mips-v1-1-eb49c9d76615@linutronix.de/