From mboxrd@z Thu Jan 1 00:00:00 1970 From: u.kleine-koenig@pengutronix.de (Uwe =?iso-8859-1?Q?Kleine-K=F6nig?=) Date: Wed, 13 May 2015 08:39:03 +0200 Subject: [PATCH v2 3/4] mtd: mxc_nand: fix truncate of unaligned oob copying In-Reply-To: <20150513051202.GI2558@tarshish> References: <20150508072432.GJ12671@pengutronix.de> <20150513051202.GI2558@tarshish> Message-ID: <20150513063903.GC28888@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, May 13, 2015 at 08:12:02AM +0300, Baruch Siach wrote: > Hi Uwe, > > On Fri, May 08, 2015 at 09:24:32AM +0200, Uwe Kleine-K?nig wrote: > > On Sun, May 03, 2015 at 10:18:53AM +0300, Baruch Siach wrote: > > > Copy to/from oob io area might not be aligned to 4 bytes. When 8 bit ECC is > > > used, the buffer size is 26. Add memcpy16_{to,from}io, and use them to avoid > > > truncating the buffer. Prefer memcpy32_{to,from}io when the buffer is properly > > > aligned for better performance. > > Did you measure this performance difference? I doubt it's worth the > > complexity given that we're talking about buffers with a size of up to > > 26 bytes. > > We'll need both memcpy16_{to,from}io and memcpy32_{to,from}io anyway. So by > "complexity" you refer to the additional alignment check and memcpy32 > fallback? I thought we could get rid of the memcpy32 variants. Where do we need memcpy32_* where memcpy16 wouldn't work? Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-K?nig | Industrial Linux Solutions | http://www.pengutronix.de/ |