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

[haibo.chen@nxp.com]

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.

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;
 
-- 
2.17.1