diff options
| author | Andrew Gabbasov <andrew_gabbasov@mentor.com> | 2014-12-25 10:22:24 -0600 |
|---|---|---|
| committer | Pantelis Antoniou <pantelis.antoniou@konsulko.com> | 2015-01-19 17:41:52 +0200 |
| commit | bf4770731c1fbd23befb1ffcd0436df2262a3199 (patch) | |
| tree | 835d2d6ac10fa3efb9a52a1af47ba96a33959332 /drivers | |
| parent | 9e41a00b572f415bbcc3d8f6fb1c6c541293655b (diff) | |
mmc: Avoid redundant switching to 1-bit bus width for MMC cards
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.
panto: Minor cosmetic edit removing superfluous parentheses.
Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Tested-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/mmc/mmc.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index 19ac4c482f..bdd7894231 100644 --- a/drivers/mmc/mmc.c +++ b/drivers/mmc/mmc.c @@ -1381,6 +1381,18 @@ 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 */ |