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SubjectRe: [PATCH V6 5/9] mmc: sdhci: Add 32-bit block count support for v4 mode
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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 <zhang.chunyan@linaro.org>
> ---
> 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.

> + 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 */
>

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