Re: [PATCH v5 6/9] EDAC/aspeed: Replace regmap with direct register access

[Borislav Petkov]

On Wed, Oct 07, 2026 at 02:13:23PM +0800, Ryan Chen wrote:
> The driver instantiates its own regmap purely as an MMIO wrapper: it has
> no register cache, uses custom .reg_read()/.reg_write() callbacks, and is
> not shared as a syscon with other drivers. So it brings nothing here
> beyond the spinlock that regmap takes around each access when fast_io is
> set.
> 
> Drop the regmap and access the registers directly with readl()/writel()
> under an explicit raw spinlock, held across the whole read-modify-write so
> the controller is unlocked once around the grouped writes rather than on
> every register write.
> 
> Annotate the register base with __guarded_by() so that, under
> CONFIG_WARN_CONTEXT_ANALYSIS, the compiler checks at build time that every
> hardware register access is performed while holding the lock.
> 
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>
> 
> ---
> Changes in v2:
> - Take the register lock with the irqsave variant in init_csrows() and in
>   aspeed_probe(); the interrupt handler takes the same lock in hardirq
>   context.
> - Move the dev_dbg() of the interrupt status register out of the
>   raw_spinlock critical section in the interrupt handler.
> - Opt aspeed_edac.o into context analysis in drivers/edac/Makefile, so
>   that the __guarded_by() annotation is actually checked.
> - Note in the interrupt handler that the counter and interrupt flag
>   fields are read-only, so writing back the read value is harmless.
> ---
>  drivers/edac/Makefile      |   1 +
>  drivers/edac/aspeed_edac.c | 131 +++++++++++++++++----------------------------
>  2 files changed, 51 insertions(+), 81 deletions(-)

https://lore.kernel.org/r/sashiko-outbox-162667@xxxxxxxxxx

-- 
Regards/Gruss,
    Boris.

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