[PATCH 4.4 133/342] mmc: sdhci-pci: Do not default to 33 Ohm driver strength for Intel SPT

From: Greg Kroah-Hartman
Date: Tue Mar 01 2016 - 18:57:00 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Adrian Hunter <adrian.hunter@xxxxxxxxx>

commit 1ca896856281d3f1ad4f6f7d4e32e2943452de23 upstream.

In some cases, the stronger 33 Ohm driver strength must not be used
so it is not a suitable default. Change it to the standard default
50 Ohm value.

The patch applies to v4.2+ except the file name changed. It is
drivers/mmc/host/sdhci-pci.c prior to v.4.4.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/mmc/host/sdhci-pci-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/mmc/host/sdhci-pci-core.c
+++ b/drivers/mmc/host/sdhci-pci-core.c
@@ -277,7 +277,7 @@ static int spt_select_drive_strength(str
if (sdhci_pci_spt_drive_strength > 0)
drive_strength = sdhci_pci_spt_drive_strength & 0xf;
else
- drive_strength = 1; /* 33-ohm */
+ drive_strength = 0; /* Default 50-ohm */

if ((mmc_driver_type_mask(drive_strength) & card_drv) == 0)
drive_strength = 0; /* Default 50-ohm */