Re: [PATCH] sdhci: Add support for hosts that are only capable of 1-bit transfers
From: Grant Likely <hidden>
Date: 2009-06-13 15:40:02
Also in:
linux-devicetree
On Thu, Jun 11, 2009 at 2:15 PM, Anton Vorontsov[off-list ref] wrote:
Some hosts (hardware configurations, or particular SD/MMC slots) may not support 4-bit bus. For example, on MPC8569E-MDS boards we can switch between serial (1-bit only) and nibble (4-bit) modes, thought we have to disable more peripherals to work in 4-bit mode. Along with some small core changes, this patch modifies sdhci-of driver, so that now it looks for "mode" property in the device-tree. Signed-off-by: Anton Vorontsov <redacted> --- Pierre, I'm not sure if a quirk would be appropriate here. If so, I can redo the patch with FORCE_1_BIT_DATA quirk. Thanks, =A0Documentation/powerpc/dts-bindings/fsl/esdhc.txt | =A0 =A02 ++ =A0drivers/mmc/host/sdhci-of.c =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0| =A0 =A07 +++++++
=A0drivers/mmc/host/sdhci-pci.c =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 |=
=A0 =A01 +
=A0drivers/mmc/host/sdhci.c =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 | =A0 =A02 +-
quoted hunk
=A04 files changed, 11 insertions(+), 1 deletions(-)diff --git a/Documentation/powerpc/dts-bindings/fsl/esdhc.txt b/Documenta=
tion/powerpc/dts-bindings/fsl/esdhc.txt
quoted hunk
index 5093ddf..298b865 100644--- a/Documentation/powerpc/dts-bindings/fsl/esdhc.txt +++ b/Documentation/powerpc/dts-bindings/fsl/esdhc.txt@@ -10,6 +10,8 @@ Required properties:=A0 - interrupts : should contain eSDHC interrupt. =A0 - interrupt-parent : interrupt source phandle. =A0 - clock-frequency : specifies eSDHC base clock frequency. + =A0- mode : specifies eSDHC mode, valid values are: "1-bit" and "4-bit"=
.
+ =A0 =A0If mode is unspecified, then 4-bit mode is assumed.
In light of Pierre's comment that 4-bit is mandatory and this is a deviation, perhaps it would be better to define an empty property to indicate that only 1-bit transfers work. Maybe something along the lines of "sdhc-1-bit-only"? g. --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.