linux-kernel - Re: [PATCH v1 for-next] spi: mchp-pci1xxxx: Updated memcpy implementation for x64 and bcm2711 processors

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Message-ID: <9f386a6d-5921-4bcf-a020-c20f9752d2d2@sirena.org.uk>
Date: Wed, 19 Mar 2025 14:33:29 +0000
From: Mark Brown <broonie@...nel.org>
To: Rengarajan.S@...rochip.com
Cc: linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
	UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v1 for-next] spi: mchp-pci1xxxx: Updated memcpy
 implementation for x64 and bcm2711 processors

On Wed, Mar 19, 2025 at 01:58:38PM +0000, Rengarajan.S@...rochip.com wrote:
> Hi Mark,
> 
> Thanks for reviewing the patch and apologies for delayed response.
> 
> On Mon, 2025-02-24 at 14:30 +0000, Mark Brown wrote:
> > [Some people who received this message don't often get email from
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You have not quoted any context from the message you're replying to so I
don't really know what you're talking about.

> I went through several patches related to similar issues, and mostsuggest handling it on a SoC basis. The reasoning is that a system
> may have an affected PCIe root complex while still having other
> devices in the SoC that can, or even require, 64-bit accesses.

> The following are some of the patches that I had looked into:
> https://lore.kernel.org/lkml/20210226140305.26356-2-nsaenzjulienne@suse.de/T/#u

That's a adding a generic 64bit-mmio-broken property - that's an example
of something that's not quirking off the SoC compatible.  Doesn't seem
to have reached mainline though.

> https://lore.kernel.org/linux-arm-kernel/c188698ca0de3ed6c56a0cf7880e1578aa753077.camel@suse.de/T/#u

> Can you please suggest any alternate methods that we could use to
> handle this in a more generic manner instead of making it Soc-specific.

That thread seems to be going down a similar direction - adding a
generic quirk that the accesses are broken.  Both these threads seem to
be suggesting something like what I was thinking of, you've got a
generic DT property or some other indication that the device can't use
64 bit accesses on this platform.

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