mmc: sdhci: Avoid swiotlb buffer being full

The commit de3ee99b097d ("mmc: Delete bounce buffer handling") deletes the
bounce buffer handling, but also causes the max_req_size for sdhci to be
increased, in case when max_segs == 1. This causes errors for sdhci-pci
Ricoh variant, about the swiotlb buffer to become full.

Fix the issue, by taking IO_TLB_SEGSIZE and IO_TLB_SHIFT into account when
deciding the max_req_size for sdhci.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Fixes: de3ee99b097d ("mmc: Delete bounce buffer handling")
Cc: <stable@vger.kernel.org> # v4.14+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 2f14334..e9290a3 100644 (file)
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -21,6 +21,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/scatterlist.h>
+#include <linux/swiotlb.h>
 #include <linux/regulator/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
@@ -3650,23 +3651,30 @@ int sdhci_setup_host(struct sdhci_host *host)
 
        spin_lock_init(&host->lock);
 
+       /*
+        * Maximum number of sectors in one transfer. Limited by SDMA boundary
+        * size (512KiB). Note some tuning modes impose a 4MiB limit, but this
+        * is less anyway.
+        */
+       mmc->max_req_size = 524288;
+
        /*
         * Maximum number of segments. Depends on if the hardware
         * can do scatter/gather or not.
         */
-       if (host->flags & SDHCI_USE_ADMA)
+       if (host->flags & SDHCI_USE_ADMA) {
                mmc->max_segs = SDHCI_MAX_SEGS;
-       else if (host->flags & SDHCI_USE_SDMA)
+       } else if (host->flags & SDHCI_USE_SDMA) {
                mmc->max_segs = 1;
-       else /* PIO */
+               if (swiotlb_max_segment()) {
+                       unsigned int max_req_size = (1 << IO_TLB_SHIFT) *
+                                               IO_TLB_SEGSIZE;
+                       mmc->max_req_size = min(mmc->max_req_size,
+                                               max_req_size);
+               }
+       } else { /* PIO */
                mmc->max_segs = SDHCI_MAX_SEGS;
-
-       /*
-        * Maximum number of sectors in one transfer. Limited by SDMA boundary
-        * size (512KiB). Note some tuning modes impose a 4MiB limit, but this
-        * is less anyway.
-        */
-       mmc->max_req_size = 524288;
+       }
 
        /*
         * Maximum segment size. Could be one segment with the maximum number