linux-kernel - Re: [PATCH v2] mailbox: pcc: support polling mode when there is no platform IRQ

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Message-ID: <20251127-lovely-real-wrasse-b1fbcd@sudeepholla>
Date: Thu, 27 Nov 2025 14:51:43 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: Andrea Tomassetti <andrea.tomassetti@...earl.com>
Cc: <lkp@...el.com>, <jassisinghbrar@...il.com>, <lenb@...nel.org>,
	<linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<oe-kbuild-all@...ts.linux.dev>, <olivier.dautricourt@...earl.com>,
	<olivierdautricourt@...il.com>, <rafael@...nel.org>,
	<thibault.cantori@...earl.com>
Subject: Re: [PATCH v2] mailbox: pcc: support polling mode when there is no
 platform IRQ

On Wed, Nov 19, 2025 at 10:01:18AM +0100, Andrea Tomassetti wrote:
> The goal is to allow clients to submit a message in both irq and polling
> mode of the pcc mailbox. The ACPI specification does not require a
> platform irq for pcc channels. Let's implement the case where it is not
> available.
> 
> peek_data is mapped to pcc_mbox_error_check_and_clear, so that it
> returns true if no error occurred while the platform processed last
> message, and therefore clients can fetch response data provided by the
> platform.
> 
> Tested-by: Thibault Cantori <thibault.cantori@...earl.com>
> Co-developed-by: Olivier Dautricourt <olivier.dautricourt@...earl.com>
> Signed-off-by: Olivier Dautricourt <olivier.dautricourt@...earl.com>
> Signed-off-by: Andrea Tomassetti <andrea.tomassetti@...earl.com>
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202511120243.soxAFpqQ-lkp@intel.com/
> Closes: https://lore.kernel.org/oe-kbuild-all/202511120558.Cln7LF6M-lkp@intel.com/
> Closes: https://lore.kernel.org/oe-kbuild-all/202511120729.R3XQNSnx-lkp@intel.com/
> ---
> v2: Fix issues reported by the kernel test robot
>   - sparse: incorrect type in argument 2 (different address spaces)
>   - acpi_pcc.c:(.text+0x69): undefined reference to `__udivdi3'
> 
>  drivers/acpi/acpi_pcc.c | 78 ++++++++++++++++++++++++++++-------------
>  drivers/mailbox/pcc.c   | 12 ++++++-

Please separate the changes to the PCC OpRegion handler and the PCC mailbox
driver into individual patches. I’ve also done some cleanup work [1], which
has been tested and resolves part of the polling vs. IRQ flag initialization
issue.

I’d appreciate it if you could rebase your changes on top of those updates to
make the review process smoother and help us move forward more quickly.

-- 
Regards,
Sudeep

[1] https://lore.kernel.org/all/20251016-pcc_mb_updates-v1-0-0fba69616f69@arm.com/