Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752299AbbHSSey (ORCPT ); Wed, 19 Aug 2015 14:34:54 -0400 Received: from smtp02.smtpout.orange.fr ([80.12.242.124]:37392 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752074AbbHSSee (ORCPT ); Wed, 19 Aug 2015 14:34:34 -0400 X-ME-Helo: belgarion.home X-ME-Date: Wed, 19 Aug 2015 20:34:33 +0200 X-ME-IP: 92.136.77.243 From: Robert Jarzmik To: Ezequiel Garcia , David Woodhouse , Brian Norris Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Robert Jarzmik Subject: [PATCH RESEND 2/2] mtd: nand: pxa3xx-nand: fix random command timeouts Date: Wed, 19 Aug 2015 20:30:15 +0200 Message-Id: <1440009015-3765-3-git-send-email-robert.jarzmik@free.fr> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1440009015-3765-1-git-send-email-robert.jarzmik@free.fr> References: <1440009015-3765-1-git-send-email-robert.jarzmik@free.fr> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2266 Lines: 64 When 2 commands are submitted in a row, and the second is very quick, the completion of the second command might never come. This happens especially if the second command is quick, such as a status read after an erase. The issue is that in the interrupt handler, the status bits are cleared after the new command is issued. There is a small temporal window where this happens : - the previous command has set the command done bit - the ready for a command bit is set - the handler submits the next command - just then, the command completes, and the command done bit is still set - the handler clears the "previous" command done bit - the handler exits In this flow, the "command done" of the next command will never trigger a new interrupt to finish the status command, as it was cleared for both commands. Fix this by clearing the status bit before submitting a new command. Signed-off-by: Robert Jarzmik --- drivers/mtd/nand/pxa3xx_nand.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c index d1a4c336de1d..d6c696798811 100644 --- a/drivers/mtd/nand/pxa3xx_nand.c +++ b/drivers/mtd/nand/pxa3xx_nand.c @@ -675,8 +675,14 @@ static irqreturn_t pxa3xx_nand_irq(int irq, void *devid) is_ready = 1; } + /* + * Clear all status bit before issuing the next command, which + * can and will alter the status bits and will deserve a new + * interrupt on its own. This lets the controller exit the IRQ + */ + nand_writel(info, NDSR, status); + if (status & NDSR_WRCMDREQ) { - nand_writel(info, NDSR, NDSR_WRCMDREQ); status &= ~NDSR_WRCMDREQ; info->state = STATE_CMD_HANDLE; @@ -697,8 +703,6 @@ static irqreturn_t pxa3xx_nand_irq(int irq, void *devid) nand_writel(info, NDCB0, info->ndcb3); } - /* clear NDSR to let the controller exit the IRQ */ - nand_writel(info, NDSR, status); if (is_completed) complete(&info->cmd_complete); if (is_ready) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/