From mboxrd@z Thu Jan 1 00:00:00 1970 From: madhu.cr@ti.com (Madhusudhan) Date: Thu, 11 Mar 2010 10:27:53 -0600 Subject: [PATCH 03/03] omap hsmmc: adaptation of sdma descriptor autoloading feature In-Reply-To: <618f0c911003110252i36d6fc31wbaef4ad7a17565b1@mail.gmail.com> References: <618f0c911003010327s290fcce1ud665b5a16392aea1@mail.gmail.com> <011301cac0b6$542b1190$544ff780@am.dhcp.ti.com> <618f0c911003110252i36d6fc31wbaef4ad7a17565b1@mail.gmail.com> Message-ID: <004401cac137$cccbf0c0$544ff780@am.dhcp.ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org > -----Original Message----- > From: svenkatr at gmail.com [mailto:svenkatr at gmail.com] On Behalf Of > Venkatraman S > Sent: Thursday, March 11, 2010 4:52 AM > To: Madhusudhan > Cc: linux-mmc at vger.kernel.org; linux-arm-kernel at lists.infradead.org; > linux-omap at vger.kernel.org > Subject: Re: [PATCH 03/03] omap hsmmc: adaptation of sdma descriptor > autoloading feature > > Madhusudhan wrote: > >> -----Original Message----- > >> From: linux-mmc-owner at vger.kernel.org [mailto:linux-mmc- > >> owner at vger.kernel.org] On Behalf Of Venkatraman S > >> Sent: Monday, March 01, 2010 5:27 AM > >> To: linux-mmc at vger.kernel.org; linux-arm-kernel at lists.infradead.org; > >> linux-omap at vger.kernel.org > >> Subject: [PATCH 03/03] omap hsmmc: adaptation of sdma descriptor > >> autoloading feature > >> > >> Start to use the sDMA descriptor autoloading feature. > >> For large datablocks, the MMC driver has to repeatedly setup, program > >> and teardown the > >> dma channel for each element of the sglist received in > omap_hsmmc_request. > >> > >> By using descriptor autoloading, transfers from / to each element of > >> the sglist is pre programmed > >> into a linked list. The sDMA driver completes the entire transaction > >> and provides a single interrupt. > >> > >> Due to this, number of dma interrupts for a typical 100MB transfer on > the > >> MMC is > >> reduced from 25000 to about 400 (approximate). Transfer speeds are > >> improved by ~5% > >> (Though it varies on the size of read / write & improves on huge > >> transfers) > >> > >> Descriptor autoloading is available only in 3630 and 4430 (as of now). > >> Hence normal DMA > >> mode is also retained. > >> > >> Tested on omap4430 sdp. > >> > >> Signed-off-by: Venkatraman S > > > > I don't see any issues with this patch except the concern I had on the > first > > patch in the series. Why is that change linked to this series? > > > Thanks. The problem was seen only in the context of using descriptor > load. Would > you prefer that I post it as a separate patch ? My point is why that change is needed for this feature to work? When DMA is completed and a callback is received the ch can be freed. Once TC is received the core is notified of the same. Can the first patch be dropped? Or do you see issues? > Regards, > Venkat.