From: Mark Brown <broonie@kernel.org> To: Vinod Koul <vinod.koul@intel.com> Cc: Sinan Kaya <okaya@codeaurora.org>, dmaengine@vger.kernel.org, timur@codeaurora.org, devicetree@vger.kernel.org, cov@codeaurora.org, jcm@redhat.com, shankerd@codeaurora.org, vikrams@codeaurora.org, marc.zyngier@arm.com, mark.rutland@arm.com, eric.auger@linaro.org, agross@codeaurora.org, arnd@arndb.de, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Dan Williams <dan.j.williams@intel.com>, Andy Shevchenko <andy.shevchenko@gmail.com>, linux-kernel@vger.kernel.org Subject: Re: [PATCH V17 2/3] dmaengine: qcom_hidma: add debugfs hooks Date: Mon, 2 May 2016 11:40:49 +0100 [thread overview] Message-ID: <20160502104049.GB6292@sirena.org.uk> (raw) In-Reply-To: <20160502092552.GC2274@localhost> [-- Attachment #1: Type: text/plain, Size: 1556 bytes --] On Mon, May 02, 2016 at 02:55:52PM +0530, Vinod Koul wrote: > On Sun, May 01, 2016 at 12:35:37AM -0400, Sinan Kaya wrote: > > My evaluation turned out negative. The regmap code is nice for bus like peripherals > > like I2C and SPI where everything is bitwise accessed. This is not the case > > in this code. > I do not entirely agree with the statements here, it does give big benefit > on our systems with MMIO. I am going to ask Mark to comment on this, he > know better and understands ARM. > I am probably going to be okay with this not using regmap and it is debug > but you should give that a try in future for better performance and ofcourse > you can add to regmap to get a better model for your device I've no idea what "this" is, sorry. All I've got here is an enormous backtrace with a bunch of the messages not even word wrapped. Please be aware that I get CCed on so much irrelevant crap that copying me into the middle of a thread about some other subsystem is likely to get missed - almost always it's review of some patch I've got no interest in. > > Barriers are really expensive on ARM. I paid very special attention in the > > code to decide when to use relaxed version vs. the readl version. I lose > > all of this optimization. Drivers should not be using the relaxed accessors, they are there for the generic code to build on not for drivers and they really need the cache flush operations. Getting the cache flush operations right, especially on ARM, isn't easy and needs detailed review. [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 473 bytes --]
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From: broonie@kernel.org (Mark Brown) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH V17 2/3] dmaengine: qcom_hidma: add debugfs hooks Date: Mon, 2 May 2016 11:40:49 +0100 [thread overview] Message-ID: <20160502104049.GB6292@sirena.org.uk> (raw) In-Reply-To: <20160502092552.GC2274@localhost> On Mon, May 02, 2016 at 02:55:52PM +0530, Vinod Koul wrote: > On Sun, May 01, 2016 at 12:35:37AM -0400, Sinan Kaya wrote: > > My evaluation turned out negative. The regmap code is nice for bus like peripherals > > like I2C and SPI where everything is bitwise accessed. This is not the case > > in this code. > I do not entirely agree with the statements here, it does give big benefit > on our systems with MMIO. I am going to ask Mark to comment on this, he > know better and understands ARM. > I am probably going to be okay with this not using regmap and it is debug > but you should give that a try in future for better performance and ofcourse > you can add to regmap to get a better model for your device I've no idea what "this" is, sorry. All I've got here is an enormous backtrace with a bunch of the messages not even word wrapped. Please be aware that I get CCed on so much irrelevant crap that copying me into the middle of a thread about some other subsystem is likely to get missed - almost always it's review of some patch I've got no interest in. > > Barriers are really expensive on ARM. I paid very special attention in the > > code to decide when to use relaxed version vs. the readl version. I lose > > all of this optimization. Drivers should not be using the relaxed accessors, they are there for the generic code to build on not for drivers and they really need the cache flush operations. Getting the cache flush operations right, especially on ARM, isn't easy and needs detailed review. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 473 bytes Desc: not available URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20160502/15836f4d/attachment.sig>
next prev parent reply other threads:[~2016-05-02 10:41 UTC|newest] Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-11 14:21 [PATCH V17 0/3] dmaengine: add Qualcomm Technologies HIDMA driver Sinan Kaya 2016-04-11 14:21 ` Sinan Kaya 2016-04-11 14:21 ` [PATCH V17 1/3] dmaengine: qcom_hidma: implement lower level hardware interface Sinan Kaya 2016-04-11 14:21 ` Sinan Kaya 2016-04-26 3:28 ` Vinod Koul 2016-04-26 3:28 ` Vinod Koul 2016-04-26 15:04 ` Sinan Kaya 2016-04-26 15:04 ` Sinan Kaya [not found] ` <571F8397.5000803-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> 2016-04-26 15:10 ` Andy Shevchenko 2016-04-26 15:10 ` Andy Shevchenko 2016-04-26 15:10 ` Andy Shevchenko 2016-04-26 15:23 ` Sinan Kaya 2016-04-26 15:23 ` Sinan Kaya 2016-04-26 16:24 ` Vinod Koul 2016-04-26 16:24 ` Vinod Koul 2016-04-26 16:24 ` Vinod Koul 2016-04-28 19:30 ` Sinan Kaya 2016-04-28 19:30 ` Sinan Kaya 2016-05-01 4:38 ` Sinan Kaya 2016-05-01 4:38 ` Sinan Kaya 2016-04-11 14:21 ` [PATCH V17 2/3] dmaengine: qcom_hidma: add debugfs hooks Sinan Kaya 2016-04-11 14:21 ` Sinan Kaya 2016-04-26 3:30 ` Vinod Koul 2016-04-26 3:30 ` Vinod Koul 2016-04-26 12:08 ` okaya 2016-04-26 12:08 ` okaya at codeaurora.org [not found] ` <b068ead6474f2ffee5acef9ea799aba3-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> 2016-04-26 16:25 ` Vinod Koul 2016-04-26 16:25 ` Vinod Koul 2016-04-26 16:25 ` Vinod Koul 2016-04-26 16:55 ` Sinan Kaya 2016-04-26 16:55 ` Sinan Kaya 2016-04-27 8:15 ` Vinod Koul 2016-04-27 8:15 ` Vinod Koul 2016-04-27 8:47 ` Marc Zyngier 2016-04-27 8:47 ` Marc Zyngier 2016-04-27 8:47 ` Marc Zyngier 2016-04-27 13:25 ` okaya 2016-04-27 13:25 ` okaya at codeaurora.org 2016-04-27 12:51 ` okaya 2016-04-27 12:51 ` okaya at codeaurora.org 2016-05-01 4:35 ` Sinan Kaya 2016-05-01 4:35 ` Sinan Kaya [not found] ` <57258799.70803-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> 2016-05-02 9:25 ` Vinod Koul 2016-05-02 9:25 ` Vinod Koul 2016-05-02 9:25 ` Vinod Koul 2016-05-02 10:40 ` Mark Brown [this message] 2016-05-02 10:40 ` Mark Brown 2016-04-11 14:21 ` [PATCH V17 3/3] dmaengine: qcom_hidma: add support for object hierarchy Sinan Kaya 2016-04-11 14:21 ` Sinan Kaya
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