From mboxrd@z Thu Jan 1 00:00:00 1970 From: alexandre.belloni@bootlin.com (Alexandre Belloni) Date: Tue, 3 Apr 2018 09:18:43 +0200 Subject: [PATCH] mtd: nand: raw: atmel: add module param to avoid using dma In-Reply-To: <8e35701f-1bfa-c9c0-62e6-48ed19d7ba37@axentia.se> References: <20180329131054.22506-1-peda@axentia.se> <20180329153322.5e2fc1e7@bbrezillon> <20180329154416.5c1a0013@bbrezillon> <20180402142249.7e076a64@bbrezillon> <20180402212843.164d5d21@bbrezillon> <8e35701f-1bfa-c9c0-62e6-48ed19d7ba37@axentia.se> Message-ID: <20180403071843.GI14180@piout.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 02/04/2018 at 22:23:17 +0200, Peter Rosin wrote: > >> No, but did it again and checked, see transcript below. > > > > I don't use devmem2. Is 'readback' information accurate or is it > > always what's been written? Because when you write 0x33 to 0xFFFFECBC, > > 0x33 is read back, but just after that, when you read it again it's 0. > > Looking at the devmem2 source, it seems very likely that the compiler > optimizes out the read and thus outputs what has been written. > At least on x86, it is not optimized out. -- Alexandre Belloni, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com