by Chunyan Zhang

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Subject: Re: [PATCH V6 5/9] mmc: sdhci: Add 32-bit block count support for v4 mode

On 27 August 2018 at 15:07, Adrian Hunter <[email protected]> wrote:
> On 24/08/18 12:20, Chunyan Zhang wrote:
>> Host Controller Version 4.10 re-defines SDMA System Address register
>> as 32-bit Block Count for v4 mode, and SDMA uses ADMA System
>> Address register (05Fh-058h) instead if v4 mode is enabled. Also
>> when using 32-bit block count, 16-bit block count register need
>> to be set to zero.
>>
>> Since using 32-bit Block Count would cause problems for auto-cmd23,
>> it can be chosen via host->quirk2.
>>
>> Signed-off-by: Chunyan Zhang <[email protected]>
>> ---
>> drivers/mmc/host/sdhci.c | 15 ++++++++++++++-
>> drivers/mmc/host/sdhci.h | 3 +++
>> 2 files changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 38d083c..05f9fff 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -1073,7 +1073,20 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
>> /* Set the DMA boundary value and block size */
>> sdhci_writew(host, SDHCI_MAKE_BLKSZ(host->sdma_boundary, data->blksz),
>> SDHCI_BLOCK_SIZE);
>> - sdhci_writew(host, data->blocks, SDHCI_BLOCK_COUNT);
>> +
>> + /*
>> + * For Version 4.10 onwards, if v4 mode is enabled, 16-bit Block Count
>> + * register need to be set to zero, 32-bit Block Count register would
>> + * be selected.
>> + */
>> + if (host->version >= SDHCI_SPEC_410 && host->v4_mode &&
>> + !(host->quirks2 & SDHCI_QUIRK2_BROKEN_32BIT_BLK_CNT)) {
>
> Because 32-bit block count is problematic but also not essential, I would
> prefer to do the quirk the other way around. i.e. SDHCI_QUIRK2_USE_32BIT_BLK_CNT
>
> I would also add a comment to the definition of
> SDHCI_QUIRK2_USE_32BIT_BLK_CNT, like:
>
> 32-bit block count may not support eMMC where upper bits of CMD23 are used
> for other purposes. Consequently we support 16-bit block count by default.
> Otherwise, SDHCI_QUIRK2_USE_32BIT_BLK_CNT can be selected to use 32-bit
> block count.

Ok, thanks Adrian!

I will address the comments and also rebase the whole patchset to v4.19-rc1.

>
>> + if (sdhci_readw(host, SDHCI_BLOCK_COUNT))
>> + sdhci_writew(host, 0, SDHCI_BLOCK_COUNT);
>> + sdhci_writew(host, data->blocks, SDHCI_32BIT_BLK_CNT);
>> + } else {
>> + sdhci_writew(host, data->blocks, SDHCI_BLOCK_COUNT);
>> + }
>> }
>>
>> static inline bool sdhci_auto_cmd12(struct sdhci_host *host,
>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>> index f3b9ebc..0a1e25f 100644
>> --- a/drivers/mmc/host/sdhci.h
>> +++ b/drivers/mmc/host/sdhci.h
>> @@ -28,6 +28,7 @@
>>
>> #define SDHCI_DMA_ADDRESS 0x00
>> #define SDHCI_ARGUMENT2 SDHCI_DMA_ADDRESS
>> +#define SDHCI_32BIT_BLK_CNT SDHCI_DMA_ADDRESS
>>
>> #define SDHCI_BLOCK_SIZE 0x04
>> #define SDHCI_MAKE_BLKSZ(dma, blksz) (((dma & 0x7) << 12) | (blksz & 0xFFF))
>> @@ -462,6 +463,8 @@ struct sdhci_host {
>> * obtainable timeout.
>> */
>> #define SDHCI_QUIRK2_DISABLE_HW_TIMEOUT (1<<17)
>> +/* Controller broken with using 32-bit block count in v4_mode */
>> +#define SDHCI_QUIRK2_BROKEN_32BIT_BLK_CNT (1<<18)
>>
>> int irq; /* Device IRQ */
>> void __iomem *ioaddr; /* Mapped address */
>>
>