From: "Koenig, Christian" <Christian.Koenig@amd.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Zhou1, Tao" <Tao.Zhou1@amd.com>,
"amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>,
"Deucher, Alexander" <Alexander.Deucher@amd.com>,
"Zhang, Hawking" <Hawking.Zhang@amd.com>,
"Li, Dennis" <Dennis.Li@amd.com>,
"broonie@kernel.org" <broonie@kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-next@vger.kernel.org" <linux-next@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kernel-build-reports@lists.linaro.org"
<kernel-build-reports@lists.linaro.org>
Subject: Re: [PATCH] drm/amdgpu: replace readq/writeq with atomic64 operations
Date: Wed, 7 Aug 2019 13:03:00 +0000 [thread overview]
Message-ID: <c613ca25-4443-f275-ea8d-6d55af10ac77@amd.com> (raw)
In-Reply-To: <20190807130043.GA6023@infradead.org>
Am 07.08.19 um 15:00 schrieb Christoph Hellwig:
> On Wed, Aug 07, 2019 at 10:55:01AM +0000, Koenig, Christian wrote:
>>>> Essentially writeq/readq doesn't seems to be available on all
>>>> architectures either.
>>> writeq/readq are provided whenever the CPU actually supports 64-bit
>>> atomic loads and stores.
>> Is there a config option which we can make the driver depend on?
>>
>> I mean that ARM doesn't support 64bit atomic loads and stores on MMIO is
>> quite a boomer for us.
> The model is to cheack if readq/writeq are defined, and if not to
> include the one of io-64-nonatomic-hi-lo.h or io-64-nonatomic-lo-hi.h.
> The reason for that is that hardware is supposed to be able to deal with
> two 32-bit writes, but it depends on the hardware if the lower or upper
> half is what commits the write.
Read, but as I understood Tao change this is not the case here.
Otherwise we would just use our WREG32/RREG32 macros in the driver.
Tao, please explain why exactly we need the WREG64/RREG64 change which
caused this.
Christian.
>
> The only 32-bit platform that claims support for readq/writeq is sh,
> and I have doubts if that actually works as expected.
next prev parent reply other threads:[~2019-08-07 13:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 2:56 [PATCH] drm/amdgpu: replace readq/writeq with atomic64 operations Tao Zhou
2019-08-07 3:09 ` Jisheng Zhang
2019-08-07 4:02 ` Alex Deucher
2019-08-07 4:03 ` Alex Deucher
2019-08-07 7:08 ` Christoph Hellwig
2019-08-07 8:53 ` Koenig, Christian
2019-08-07 10:41 ` Christoph Hellwig
2019-08-07 10:55 ` Koenig, Christian
2019-08-07 12:59 ` Mark Brown
2019-08-07 13:00 ` Koenig, Christian
2019-08-07 13:07 ` Christoph Hellwig
2019-08-07 13:00 ` Christoph Hellwig
2019-08-07 13:03 ` Koenig, Christian [this message]
2019-08-07 18:00 ` Alex Deucher
2019-08-08 19:25 ` Guenter Roeck
2019-08-08 19:33 ` Alex Deucher
2019-08-09 9:04 ` Koenig, Christian
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