Best Regards
Jerry Huang

-----Original Message-----
From: Girish K S [mailto:girish.shivananjappa@linaro.org]
Sent: Friday, September 21, 2012 5:56 PM
To: Huang Changming-R66093
Cc: linux-mmc@vger.kernel.org; Huang Changming-R66093; Xie Shaohui-B21989;
Anton Vorontsov
Subject: Re: [PATCH v2] powerpc/esdhc: disable CMD23 for some Freescale
SoCs

On 21 September 2012 14:38,  [off-list ref] wrote:

quoted

From: Jerry Huang <redacted>

CMD23 causes lots of errors in kernel on some freescale SoCs (P1020,
P1021, P1022, P1024, P1025 and P4080) when mmc card used, which is
because these controllers does not support CMD23, but even on SoCs
which declare CMD23 is supported, so we'll not use CMD23.

Signed-off-by: Jerry Huang <redacted>
Signed-off-by: Shaohui Xie <redacted>
CC: Anton Vorontsov <redacted>
---
changes for v2:
        - discard the property mode and add the processor detection

 drivers/mmc/host/sdhci-pltfm.c |   32 ++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci.c       |    3 +++
 include/linux/mmc/sdhci.h      |    1 +
 3 files changed, 36 insertions(+)

diff --git a/drivers/mmc/host/sdhci-pltfm.c

b/drivers/mmc/host/sdhci-pltfm.c index d9a4ef4..ad55181 100644

--- a/drivers/mmc/host/sdhci-pltfm.c
+++ b/drivers/mmc/host/sdhci-pltfm.c

@@ -93,6 +93,36 @@ void sdhci_get_of_property(struct platform_device

*pdev) {}  #endif /* CONFIG_OF */
EXPORT_SYMBOL_GPL(sdhci_get_of_property);

+static const u32 processor_table[] = {
+       /* P1020 Dual/Single core */
+       0x80EC00, 0x80E400, 0x80ED00, 0x80E500,
+       /* P1021 Dual/Single core */
+       0x80EC01, 0x80E401, 0x80ED01, 0x80E501,
+       /* P1022 Dual/Single core */
+       0x80EE00, 0x80E600, 0x80EF00, 0x80E700,
+       /* P1024 Dual/Single core */
+       0x80EC02, 0x80E402, 0x80ED02, 0x80E502,
+       /* P1025 Dual/Single core */
+       0x80EC03, 0x80E403, 0x80ED03, 0x80E503,
+       /* P4080 and P4040 */
+       0x820000, 0x820800, 0x820100, 0x820900 };
+
+void sdhci_detect_limitation(struct platform_device *pdev) {
+       struct sdhci_host *host = platform_get_drvdata(pdev);
+       u32 svr = mfspr(SPRN_SVR) >> 8;
+       u32 table_size = ARRAY_SIZE(processor_table);
+       int i;
+
+       for (i = 0; i < table_size; i++) {
+               if (processor_table[i] == svr) {
+                       host->quirks2 |= SDHCI_QUIRK2_HOST_NO_CMD23;
+                       break;
+               }
+       }
+}
+

These changes are specific to powerpc platform. And sdhci-pltfm.c is a
generic sdhci file. adding platform Soc code into this is not good.
You can find how other Socs are making use of this file by creating a new
Soc specific extension file.
 Similarly you can have something like sdhci-powerpc.c

Yes, it is the better way, I once thought about this way. But, one callback function will be added.