[PATCH 21/38] mmc: sdhci: hack up driver to make it more compliant with UHS-1

[Russell King - ARM Linux]

On Fri, Apr 25, 2014 at 02:38:20PM +0200, Markus Pargmann wrote:
> Hi,
> 
> On Wed, Apr 23, 2014 at 08:07:57PM +0100, Russell King wrote:
> > Patch suggested by Dong Aisheng <dongas86 at gmail.com>, this avoids
> > additional clock start/stop cycles during the transition to 1.8V
> > signalling mode.
> > 
> > Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> 
> I tested the series on imx6s with a RIoT board. With this patch applied
> the RIoT board emmc does not work. Here is the output of the board:

Unfortunately, I don't have any emmc sdhci using devices, so this is
a combination I can't test myself.

What would be useful is to find out which of the two changes in there
is the cause - can you try with just the change to
sdhci_do_start_signal_voltage_switch applied, iow just this change:

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 748333ba6e96..0bcef2d42da4 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1757,9 +1748,6 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
 		ctrl |= SDHCI_CTRL_VDD_180;
 		sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
 
-		/* Wait for 5ms */
-		usleep_range(5000, 5500);
-
 		/* 1.8V regulator output should be stable within 5 ms */
 		ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 		if (ctrl & SDHCI_CTRL_VDD_180)

Thanks.

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