linux-kernel - Re: [PATCH 03/14] mailbox: pcc: Drop unnecessary endianness conversion of pcc

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Message-ID: <20250305103648.7e2ajxlkwza7axzc@bogus>
Date: Wed, 5 Mar 2025 10:36:48 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: "lihuisong (C)" <lihuisong@...wei.com>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jassi Brar <jassisinghbrar@...il.com>,
	Adam Young <admiyo@...amperecomputing.com>
Subject: Re: [PATCH 03/14] mailbox: pcc: Drop unnecessary endianness
 conversion of pcc_hdr.flags

On Wed, Mar 05, 2025 at 12:02:13PM +0800, lihuisong (C) wrote:
> 
> 在 2025/3/3 18:51, Sudeep Holla 写道:
> > The Sparse static checker flags a type mismatch warning related to
> > endianness conversion:
> > 
> >    |  warning: incorrect type in argument 1 (different base types)
> >    |     expected restricted __le32 const [usertype] *p
> >    |     got unsigned int *
> > 
> > This is because an explicit endianness conversion (le32_to_cpu()) was
> > applied unnecessarily to a pcc_hdr.flags field that is already in
> > little-endian format.
> > 
> > The PCC driver is only enabled on little-endian kernels due to its
> > dependency on ACPI and EFI, making the explicit conversion unnecessary.
> How to confirm ACPI works only on little-endian?

Sorry I didn't notice this question. ACPI depends on ARCH_SUPPORTS_ACPI
and it is selected only from EFI which is disabled if CPU_BIG_ENDIAN=y

--
Regards,
Sudeep