From 7efaa8677ffd07d54d0122b5e92f29b74a36ad39 Mon Sep 17 00:00:00 2001 From: Ezequiel Garcia Date: Thu, 19 Dec 2013 06:08:03 -0300 Subject: [PATCH 162/203] mtd: nand: pxa3xx: Clear need_wait flag when starting a command Currently the driver assumes all commands will eventually trigger a RnB transition, and thus a "device is ready" IRQ. This assumption means that on every issued command, the dev_ready completion handler is init'ed and the need_wait flag is set. However this is incorrect: some commands (such as NAND_CMD_STATUS) don't make the device 'busy' and thus a RnB transition never occurs. Given, the NAND core never calls waitfunc() after such commands, this is not a problem. Therefore, it's possible to only clear the need_wait flag on every command that is started. This fixes a current bug that can be reproduced on PXA boards by writing blank (all 0xff'ed) to a page: 1. The kernel issues NAND_CMD_STATUS and sets need_wait=1. The flag won't be cleared for this command since no RnB transition is involved. 2. NAND_CMD_PAGEPROG is issued but since the data is blank, the driver decides not to execute the command (and no IRQ activity is involved). 3. The NAND core calls waitfunc() and waits for the dev_ready completion, which will never end since the device _is_ already ready. Tested-by: Arnaud Ebalard Signed-off-by: Ezequiel Garcia --- drivers/mtd/nand/pxa3xx_nand.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/mtd/nand/pxa3xx_nand.c +++ b/drivers/mtd/nand/pxa3xx_nand.c @@ -694,6 +694,7 @@ static void prepare_start_command(struct info->retcode = ERR_NONE; info->ecc_err_cnt = 0; info->ndcb3 = 0; + info->need_wait = 0; switch (command) { case NAND_CMD_READ0: