From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from buildserver.ru.mvista.com (unknown [85.21.88.6]) by ozlabs.org (Postfix) with ESMTP id 07061DE02F for ; Sat, 29 Mar 2008 06:10:56 +1100 (EST) Date: Fri, 28 Mar 2008 22:10:54 +0300 From: Anton Vorontsov To: Scott Wood Subject: [PATCH] mtd/nand/fsl_elbc_nand: workaround for hangs during nand write [was: Re: [PATCH] mtd/nand/fsl_elbc_nand: workaround for hangs on MPC837X] Message-ID: <20080328191054.GA30765@localhost.localdomain> References: <20080328184303.GA25882@localhost.localdomain> <47ED3EC5.8030508@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf8 In-Reply-To: <47ED3EC5.8030508@freescale.com> Cc: linuxppc-dev@ozlabs.org, linux-mtd@lists.infradead.org Reply-To: avorontsov@ru.mvista.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Mar 28, 2008 at 01:53:57PM -0500, Scott Wood wrote: > Anton Vorontsov wrote: > >@@ -495,6 +495,16 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, > >const u8 *buf, int len) > > } > > > > memcpy_toio(&ctrl->addr[ctrl->index], buf, len); > >+#ifdef CONFIG_PPC_MPC837x > >+ /* > >+ * This is workaround for the weird elbc hangs on the MPC837X CPUs, > >+ * Scott Wood says: "...perhaps difference in how long it takes a > >+ * write to make it through the localbus compared to a write to IMMR > >+ * is causing problems, and sync isn't helping for some reason." > >+ * Reading back the last byte helps though. > >+ */ > >+ in_8(&ctrl->addr[ctrl->index] + len - 1); > >+#endif > > Let's do it regardless of chip -- odds are the issue exists on all > implementations, and it's just a function of what frequencies things are > running at. Ok. - - - - From: Anton Vorontsov Subject: mtd/nand/fsl_elbc_nand: workaround for hangs during nand write Using current driver elbc sometimes hangs during nand write. Reading back last byte helps though (thanks to Scott Wood for the idea). Signed-off-by: Anton Vorontsov --- drivers/mtd/nand/fsl_elbc_nand.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/drivers/mtd/nand/fsl_elbc_nand.c b/drivers/mtd/nand/fsl_elbc_nand.c index 378b7aa..2f4ce2a 100644 --- a/drivers/mtd/nand/fsl_elbc_nand.c +++ b/drivers/mtd/nand/fsl_elbc_nand.c @@ -480,7 +480,7 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len) struct fsl_elbc_ctrl *ctrl = priv->ctrl; unsigned int bufsize = mtd->writesize + mtd->oobsize; - if (len < 0) { + if (len <= 0) { dev_err(ctrl->dev, "write_buf of %d bytes", len); ctrl->status = 0; return; @@ -495,6 +495,15 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len) } memcpy_toio(&ctrl->addr[ctrl->index], buf, len); + /* + * This is workaround for the weird elbc hangs during nand write, + * Scott Wood says: "...perhaps difference in how long it takes a + * write to make it through the localbus compared to a write to IMMR + * is causing problems, and sync isn't helping for some reason." + * Reading back the last byte helps though. + */ + in_8(&ctrl->addr[ctrl->index] + len - 1); + ctrl->index += len; } -- 1.5.2.2