Re: [PATCH v2 1/2] nvmem: sunxi_sid: Always use 32-bit MMIO reads

[Jernej Škrabec]

Dne nedelja, 01. januar 2023 ob 19:33:15 CET je Samuel Holland napisal(a):
> The SID SRAM on at least some SoCs (A64 and D1) returns different values
> when read with bus cycles narrower than 32 bits. This is not immediately
> obvious, because memcpy_fromio() uses word-size accesses as long as
> enough data is being copied.
> 
> The vendor driver always uses 32-bit MMIO reads, so do the same here.
> This is faster than the register-based method, which is currently used
> as a workaround on A64. And it fixes the values returned on D1, where
> the SRAM method was being used.
> 
> The special case for the last word is needed to maintain .word_size == 1
> for sysfs ABI compatibility, as noted previously in commit de2a3eaea552
> ("nvmem: sunxi_sid: Optimize register read-out method").
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 07ae4fde9efa ("nvmem: sunxi_sid: Add support for D1 variant")
> Tested-by: Heiko Stuebner <heiko@xxxxxxxxx>
> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx>

Reviewed-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>

Best regards,
Jernej