If all the commands switching an MMC card to 4- or 8-bit bus width fail,
and the bus width for the controller and the driver is still set
to default 1 bit, there is no need to send one more command to switch
the card to 1-bit bus width. Also, if the card or host controller do not
support wider bus widths, there is no need to send a switch command at all.
However, if one of switch commands succeeds, but the subsequent ext_csd
fields comparison fails, the card should be switched to some other bus width
(next in the list for the loop), or to default 1-bit bus width as a last
resort. That's why it would be incorrect to just remove the 1-bit bus width
case from the list, it should still be processed in some cases.
Signed-off-by: Andrew Gabbasov <andrew_gabba...@mentor.com>
Tested-by: Alexey Brodkin <abrod...@synopsys.com>
---
drivers/mmc/mmc.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 1eb9c27..c0cf318 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -1139,6 +1139,18 @@ static int mmc_startup(struct mmc *mmc)
unsigned int caps = ext_to_hostcaps[extw];
/*
+ * If the bus width is still not changed,
+ * don't try to set the default again.
+ * Otherwise, recover from switch attempts
+ * by switching to 1-bit bus width.
+ */
+ if ((extw == EXT_CSD_BUS_WIDTH_1) &&
+ (mmc->bus_width == 1)) {
+ err = 0;
+ break;
+ }
+
+ /*
* Check to make sure the card and controller support
* these capabilities
*/
--
2.1.0
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