Re: [PATCH] alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2

From: Sinan Kaya
Date: Tue Apr 17 2018 - 14:43:10 EST

On 4/16/2018 6:16 PM, Sinan Kaya wrote:
> memory-barriers.txt has been updated with the following requirement.
> "When using writel(), a prior wmb() is not needed to guarantee that the
> cache coherent memory writes have completed before writing to the MMIO
> region."
> Current writeX() and iowriteX() implementations on alpha are not
> satisfying this requirement as the barrier is after the register write.
> Move mb() in writeX() and iowriteX() functions to guarantee that HW
> observes memory changes before performing register operations.
> Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx>
> Reported-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> arch/alpha/kernel/io.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)

Sorry for catching this late but this also needs to go to 4.17 after

I missed the writel() implementation on arch/alpha/kernel/io.c file
on my first patch.

Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
To unsubscribe from this list: send the line "unsubscribe linux-alpha" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at