Re: [PATCH] mmc: sdhci: disable ADMA when PAGE SIZE is 64K

[Adrian Hunter <adrian.hunter@intel.com>]

On 27/10/2021 05:47, haibo.chen@nxp.com wrote:
> From: Haibo Chen <haibo.chen@nxp.com>
> 
> For ADMA with quirks SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC, it limit
> the max segment size as 64K-1. Currently, linux kernel support
> 4K/16K/64K PAGE_SIZE. If choose 64K PAGE_SIZE, sdhci in ADMA mode
> with the upper quirks will meet issue.
> 
> Though mmc driver give block layer the max segment size through
> blk_queue_max_segment_size(), but in this function, it will compare
> the argument with PAGE_SIZE, and will choose PAGE_SIZE if the argument
> is smaller than PAGE_SIZE. When PAGE_SIZE is 64K, finally the mmc
> request queue will get 64K as the max segment size. Once the sg data
> length=64K, ADMA will meet issue. For this case, need to disable ADMA
> mode.

Sorry, I didn't look closely enough at this.

For the 64K PAGE_SIZE case, did you try blk_queue_virt_boundary()
with a 32K mask instead of blk_queue_max_segment_size() ?
e.g. a hack for testing purposes like this:

diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index b15c034b42fb..4c3a9d999500 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -376,8 +376,7 @@ static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card)
 	 * both blk_queue_max_segment_size().
 	 */
 	if (!host->can_dma_map_merge)
-		blk_queue_max_segment_size(mq->queue,
-			round_down(host->max_seg_size, block_size));
+		blk_queue_virt_boundary(mq->queue, 0x7fff);
 
 	dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
 



> 
> Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
> ---
>  drivers/mmc/host/sdhci.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index dbe87995596c..47e0c0156b94 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -4187,6 +4187,12 @@ int sdhci_setup_host(struct sdhci_host *host)
>  		host->flags &= ~SDHCI_USE_ADMA;
>  	}
>  
> +	if ((host->quirks & SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC) &&
> +		PAGE_SIZE >= 65536 && (host->flags & SDHCI_USE_ADMA)) {
> +		DBG("Disabling ADMA as it don't support >= 64K PAGE_SIZE\n");
> +		host->flags &= ~SDHCI_USE_ADMA;
> +	}
> +
>  	if (sdhci_can_64bit_dma(host))
>  		host->flags |= SDHCI_USE_64_BIT_DMA;
>  
>