Hi Cristoph,

>From: Pekon Gupta <pe...@ti.com>
>>From: Christoph Fritz [mailto:chf.fr...@googlemail.com]
>>
>>Most dt omap3 boards configure nand-ecc-opt as bch8. Due
>>to lack of hardware elm support, bch8 software implementation
>>gets set.
>>
>>Since commit 0611c41934ab35ce84dea "ARM: OMAP2+: gpmc: update
>>gpmc_hwecc_bch_capable() for new platforms and ECC schemes",
>>nand support stops working.
>>
>>This patch allows ecc software fallback.
>
>Pleas add following tag at top of commit message.
>
>Fixes: commit 0611c41934ab35ce84dea34ab291897ad3cbc7be
>ARM: OMAP2+: gpmc: update gpmc_hwecc_bch_capable() for new platforms and ECC 
>schemes
>
>And please mark it for 3.15 stable if this gets accepted after 3.15-rcx.
>Cc: <sta...@vger.kernel.org> # 3.15.x+
>
>
>>---
>> arch/arm/mach-omap2/gpmc-nand.c |   16 ++++++----------
>> 1 file changed, 6 insertions(+), 10 deletions(-)
>>
>>diff --git a/arch/arm/mach-omap2/gpmc-nand.c b/arch/arm/mach-omap2/gpmc-nand.c
>>index 4349e82..52c4834 100644
>>--- a/arch/arm/mach-omap2/gpmc-nand.c
>>+++ b/arch/arm/mach-omap2/gpmc-nand.c
>>@@ -43,13 +43,17 @@ static struct platform_device gpmc_nand_device = {
>>      .resource       = gpmc_nand_resource,
>> };
>>
>>-static bool gpmc_hwecc_bch_capable(enum omap_ecc ecc_opt)
>>+static bool gpmc_ecc_bch_capable(enum omap_ecc ecc_opt)
>
>I don't think this renaming is really required with this fix, so please
>drop it and just keep it simple only for OMAP3 fix.
>
>
>> {
>>      /* platforms which support all ECC schemes */
>>      if (soc_is_am33xx() || cpu_is_omap44xx() ||
>>               soc_is_omap54xx() || soc_is_dra7xx())
>>              return 1;
>>
>>+     if ((ecc_opt == OMAP_ECC_BCH4_CODE_HW_DETECTION_SW) ||
>>+             (ecc_opt == OMAP_ECC_BCH8_CODE_HW_DETECTION_SW))
>>+             return 1;
>>+
>
>Note: Some very old legacy platforms have initial version of GPMC engine
>which only supports Hamming ECC, and not BCH ECC scheme, so lets
>filter them out to maintain backward compatibility.
>
>(1) As per TRM, OMAP2 platform does not support BCH ECC schemes,
>      So please filter out OMAP2 devices from this check ...
>
>(2) I don't know the history but below comment says:
>"* For now, assume 4-bit mode is only supported on OMAP3630 ES1.x, x>=1"
>
>if ((ecc_opt == OMAP_ECC_BCH4_CODE_HW_DETECTION_SW) ||
>        (ecc_opt == OMAP_ECC_BCH8_CODE_HW_DETECTION_SW))  {
>       if (cpu_is_omap24xx())
>               return 0;
>       else if (cpu_is_omap3630() && (GET_OMAP_REVISION() == 0))
>               return 0;
>       else
>               return 1;
>}
>
>
>>      /* OMAP3xxx do not have ELM engine, so cannot support ECC schemes
>>       * which require H/W based ECC error detection */
>>      if ((cpu_is_omap34xx() || cpu_is_omap3630()) &&
>>@@ -57,14 +61,6 @@ static bool gpmc_hwecc_bch_capable(enum omap_ecc ecc_opt)
>>               (ecc_opt == OMAP_ECC_BCH8_CODE_HW)))
>>              return 0;
>>
>>-     /*
>>-      * For now, assume 4-bit mode is only supported on OMAP3630 ES1.x, x>=1
>>-      * and AM33xx derivates. Other chips may be added if confirmed to work.
>>-      */
>>-     if ((ecc_opt == OMAP_ECC_BCH4_CODE_HW_DETECTION_SW) &&
>>-         (!cpu_is_omap3630() || (GET_OMAP_REVISION() == 0)))
>>-             return 0;
>>-
>Thanks for removing this, I too wasn't confident of this either.
>
>
>>      /* legacy platforms support only HAM1 (1-bit Hamming) ECC scheme */
>>      if (ecc_opt == OMAP_ECC_HAM1_CODE_HW)
>>              return 1;
>>@@ -140,7 +136,7 @@ int gpmc_nand_init(struct omap_nand_platform_data 
>>*gpmc_nand_data,
>>
>>      gpmc_update_nand_reg(&gpmc_nand_data->reg, gpmc_nand_data->cs);
>>
>>-     if (!gpmc_hwecc_bch_capable(gpmc_nand_data->ecc_opt)) {
>>+     if (!gpmc_ecc_bch_capable(gpmc_nand_data->ecc_opt)) {
>
>Please drop this renaming from this patch.
>
>>              dev_err(dev, "Unsupported NAND ECC scheme selected\n");
>>              return -EINVAL;
>>      }
>>--
>>1.7.10.4
>
>You may send this patch separately apart from the series, so that
>this gets accepted in current 3.15-rcx.
>
>with regards, Pekon

Do you plan to re-spin this patch with above comments, and mark it for stable?
It would be helpful for all OMAP3 users.


with regards, pekon
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