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

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Message-ID: <20250212140412-7a4be486-21ee-4ab8-9371-9f732e92bf7b@linutronix.de>
Date: Wed, 12 Feb 2025 14:12:10 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Richard Fitzgerald <rf@...nsource.cirrus.com>
Cc: Simon Trimmer <simont@...nsource.cirrus.com>, 
	Charles Keepax <ckeepax@...nsource.cirrus.com>, Mark Brown <broonie@...nel.org>, patches@...nsource.cirrus.com, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] firmware: cs_dsp: Remove usage of GFP_DMA

On Tue, Feb 11, 2025 at 05:21:08PM +0000, Richard Fitzgerald wrote:
> On 11/02/2025 5:03 pm, Thomas Weißschuh wrote:
> > Also drop the bounce buffer in cs_dsp_coeff_write_ctrl_raw().
> > 
> > The bounce buffer in cs_dsp_coeff_write_ctrl_raw() could theoretically
> > also be removed. That would be a functional change as the output may be
> > modified in error cases.
> > As I don't know the driver very well I left that part out.
> > 
> > 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
> > cs_dsp is unnecessary in the first place.
> > 
> 
> You're sure that all I2C and SPI bus controllers now handle non-DMA-safe
> buffers correctly?

No, but as mentioned in patch 1, many transfers are done from and to
on-stack buffers and these seem to work.
Anyways, I fixed the DMA zone issue on MIPS in general [0],
feel free to disregard the series.

[0] https://lore.kernel.org/r/20250212-kunit-mips-v1-0-eb49c9d76615@linutronix.de
(lore is broken right now, so it will take some time to show up)

> > Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
> > ---
> > Thomas Weißschuh (2):
> >        firmware: cs_dsp: Remove usage of GFP_DMA
> >        firmware: cs_dsp: Remove bounce buffer in cs_dsp_coeff_write_ctrl_raw()
> > 
> >   drivers/firmware/cirrus/cs_dsp.c | 15 +++------------
> >   1 file changed, 3 insertions(+), 12 deletions(-)
> > ---
> > base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
> > change-id: 20250211-cs_dsp-gfp_dma-0581bdd09dd5
> > 
> > Best regards,
>