[ 3.5.y.z extended stable ] Patch "mmc: atmel-mci: pio hang on block errors" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    mmc: atmel-mci: pio hang on block errors

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From bc823ddd407b1b32f44ea2e62c3de3bcc4827cdf Mon Sep 17 00:00:00 2001
From: Terry Barnaby <terry at beam.ltd.uk>
Date: Mon, 8 Apr 2013 12:05:47 -0400
Subject: [PATCH] mmc: atmel-mci: pio hang on block errors

commit bdbc5d0c60f3e9de3eeccf1c1a18bdc11dca62cc upstream.

The driver is doing, by default, multi-block reads. When a block error
occurs, card/block.c instigates a single block read: "mmcblk0: retrying
using single block read".  It leaves the sg chain intact and just changes
the length attribute for the first sg entry and the overall sg_len
parameter.  When atmci_read_data_pio is called to read the single block
of data it ignores the sg_len and expects to read more than 512 bytes as
it sees there are multiple items in the sg list. No more data comes as
the controller has only been commanded to get one block.

Signed-off-by: Terry Barnaby <terry at beam.ltd.uk>
Acked-by: Ludovic Desroches <ludovic.desroches at atmel.com>
Signed-off-by: Chris Ball <cjb at laptop.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/mmc/host/atmel-mci.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 77e998b..ac472be 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -175,6 +175,7 @@ struct atmel_mci {
 	void __iomem		*regs;

 	struct scatterlist	*sg;
+	unsigned int		sg_len;
 	unsigned int		pio_offset;
 	unsigned int		*buffer;
 	unsigned int		buf_size;
@@ -819,6 +820,7 @@ static u32 atmci_prepare_data(struct atmel_mci *host, struct mmc_data *data)
 	data->error = -EINPROGRESS;

 	host->sg = data->sg;
+	host->sg_len = data->sg_len;
 	host->data = data;
 	host->data_chan = NULL;

@@ -1751,7 +1753,8 @@ static void atmci_read_data_pio(struct atmel_mci *host)
 			if (offset == sg->length) {
 				flush_dcache_page(sg_page(sg));
 				host->sg = sg = sg_next(sg);
-				if (!sg)
+				host->sg_len--;
+				if (!sg || !host->sg_len)
 					goto done;

 				offset = 0;
@@ -1764,7 +1767,8 @@ static void atmci_read_data_pio(struct atmel_mci *host)

 			flush_dcache_page(sg_page(sg));
 			host->sg = sg = sg_next(sg);
-			if (!sg)
+			host->sg_len--;
+			if (!sg || !host->sg_len)
 				goto done;

 			offset = 4 - remaining;
@@ -1815,7 +1819,8 @@ static void atmci_write_data_pio(struct atmel_mci *host)
 			nbytes += 4;
 			if (offset == sg->length) {
 				host->sg = sg = sg_next(sg);
-				if (!sg)
+				host->sg_len--;
+				if (!sg || !host->sg_len)
 					goto done;

 				offset = 0;
@@ -1829,7 +1834,8 @@ static void atmci_write_data_pio(struct atmel_mci *host)
 			nbytes += remaining;

 			host->sg = sg = sg_next(sg);
-			if (!sg) {
+			host->sg_len--;
+			if (!sg || !host->sg_len) {
 				atmci_writel(host, ATMCI_TDR, value);
 				goto done;
 			}
--
1.8.1.2