[ 102/104] mmc: atmel-mci: pio hang on block errors

Greg Kroah-Hartman
2013-05-06T23:15:35Z

From: Terry Barnaby <terry@beam.ltd.uk>

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@beam.ltd.uk>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mmc/host/atmel-mci.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -178,6 +178,7 @@ struct atmel_mci {
void __iomem *regs;

struct scatterlist *sg;
+ unsigned int sg_len;
unsigned int pio_offset;
unsigned int *buffer;
unsigned int buf_size;
@@ -892,6 +893,7 @@ static u32 atmci_prepare_data(struct atm
data->error = -EINPROGRESS;

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

@@ -1826,7 +1828,8 @@ static void atmci_read_data_pio(struct a
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;
@@ -1839,7 +1842,8 @@ static void atmci_read_data_pio(struct a

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;
@@ -1890,7 +1894,8 @@ static void atmci_write_data_pio(struct
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;
@@ -1904,7 +1909,8 @@ static void atmci_write_data_pio(struct
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;
}