From mboxrd@z Thu Jan 1 00:00:00 1970 From: zonque@gmail.com (Daniel Mack) Date: Mon, 11 Jul 2011 20:53:23 +0200 Subject: [PATCH 3/4] MTD: pxa3xx_nand: enable multiple chip select support In-Reply-To: <4E1B3ECC.5080308@compulab.co.il> References: <1309319494-17951-1-git-send-email-leiwen@marvell.com> <1309771536-10597-4-git-send-email-leiwen@marvell.com> <4E1411BB.4010000@compulab.co.il> <4E1B3ECC.5080308@compulab.co.il> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Jul 11, 2011 at 8:19 PM, Igor Grinberg wrote: > On 07/11/11 17:49, Daniel Mack wrote: >> Lei, any ideas, can you reproduce this? To avoid further regressions >> of this driver, you really should have a system on which you can test >> suspend and resume after each commit. > > I think the problem is that on PXA3xx resume from S2/S3 involves bootloader. > If I remember correctly, the BootROM reads the bootloader from the boot device > regardless of the reset cause (S2/S3 resume is kind a reset for PXA3xx). At least not in our case. The first level bootloader is entered on resume just as it is on a POR event, with the exception that the D3S bit in the ASCR register is set in this case. We unconditionally initialize the static and dynamic memory controllers and then either jump to the routine that initializes the NAND controller, read the 2nd level loader and pass control to it. Or (in the resume case) we just jump to the address stored at the RAM address 0x80000000 (which has been set to cpu_resume previously) and thus enter the kernel again. No NAND operations in the game in this case, and this has always worked fine. > Then the bootloader must decide what should be done according to the reset cause. > This means, that the BootROM already configures the NAND flash > (if it is the boot device) and pxa3xx_nand driver should just get on with it > and don't try to reconfigure? I think the problem is just the opposite. The driver expects the setup registers to retain their state over suspend, and doesn't write them again, and this causes operations to fail after resume. Daniel