Re: [RFT 00/13] iomap: Constify ioreadX() iomem argument

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


Hi Geert,

Le 08/01/2020 à 09:43, Geert Uytterhoeven a écrit :
Hi Christophe,

On Wed, Jan 8, 2020 at 9:35 AM Christophe Leroy <christophe.leroy@xxxxxx> wrote:
Le 08/01/2020 à 09:18, Krzysztof Kozlowski a écrit :
On Wed, 8 Jan 2020 at 09:13, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
On Wed, Jan 8, 2020 at 9:07 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
On Tue, Jan 7, 2020 at 5:53 PM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
The ioread8/16/32() and others have inconsistent interface among the
architectures: some taking address as const, some not.

It seems there is nothing really stopping all of them to take
pointer to const.

Shouldn't all of them take const volatile __iomem pointers?
It seems the "volatile" is missing from all but the implementations in

As my "volatile" comment applies to iowrite*(), too, probably that should be
done in a separate patch.

Hence with patches 1-5 squashed, and for patches 11-13:
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

I'll add to this one also changes to ioreadX_rep() and add another
patch for volatile for reads and writes. I guess your review will be
appreciated once more because of ioreadX_rep()

volatile should really only be used where deemed necessary:

It is said: " ...  accessor functions might use volatile on
architectures where direct I/O memory access does work. Essentially,
each accessor call becomes a little critical section on its own and
ensures that the access happens as expected by the programmer."

That is exactly the use case here: all above are accessor functions.

Why would ioreadX() not need volatile, while readY() does?

My point was: it might be necessary for some arches and not for others.

And as pointed by Arnd, the volatile is really only necessary for the dereference itself, should the arch use dereferencing.

So I guess the best would be to go in the other direction: remove volatile keyword wherever possible instead of adding it where it is not needed.


linux-snps-arc mailing list

[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux