[PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host

[Alexandre Courbot]

Set the DMA mask in sdhci_add_host() after we determined the
capabilities of the device. 64-bit devices in particular are given the
proper mask that ensures bounce buffers are not used.

Also disable DMA if no proper DMA mask can be set, as the DMA-API
documentation specifies.

Signed-off-by: Alexandre Courbot <acour...@nvidia.com>
---
 drivers/mmc/host/sdhci.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index fd9139947fa3..920e1c996280 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2857,6 +2857,36 @@ struct sdhci_host *sdhci_alloc_host(struct device *dev,
 
 EXPORT_SYMBOL_GPL(sdhci_alloc_host);
 
+static int sdhci_set_dma_mask(struct sdhci_host *host)
+{
+       struct mmc_host *mmc = host->mmc;
+       struct device *dev = mmc_dev(mmc);
+       int ret = -EINVAL;
+
+       if (host->quirks2 & SDHCI_QUIRK2_BROKEN_64_BIT_DMA)
+               host->flags &= ~SDHCI_USE_64_BIT_DMA;
+
+       /* Try 64-bit mask if hardware is capable  of it */
+       if (host->flags & SDHCI_USE_64_BIT_DMA) {
+               ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
+               if (ret) {
+                       pr_warn("%s: Failed to set 64-bit DMA mask.\n",
+                               mmc_hostname(mmc));
+                       host->flags &= ~SDHCI_USE_64_BIT_DMA;
+               }
+       }
+
+       /* 32-bit mask as default & fallback */
+       if (ret) {
+               ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
+               if (ret)
+                       pr_warn("%s: Failed to set 32-bit DMA mask.\n",
+                               mmc_hostname(mmc));
+       }
+
+       return ret;
+}
+
 int sdhci_add_host(struct sdhci_host *host)
 {
        struct mmc_host *mmc;
@@ -2932,13 +2962,17 @@ int sdhci_add_host(struct sdhci_host *host)
                host->flags |= SDHCI_USE_64_BIT_DMA;
 
        if (host->flags & (SDHCI_USE_SDMA | SDHCI_USE_ADMA)) {
-               if (host->ops->enable_dma) {
-                       if (host->ops->enable_dma(host)) {
-                               pr_warn("%s: No suitable DMA available - 
falling back to PIO\n",
-                                       mmc_hostname(mmc));
-                               host->flags &=
-                                       ~(SDHCI_USE_SDMA | SDHCI_USE_ADMA);
-                       }
+               ret = sdhci_set_dma_mask(host);
+
+               if (!ret && host->ops->enable_dma)
+                       ret = host->ops->enable_dma(host);
+
+               if (ret) {
+                       pr_warn("%s: No suitable DMA available - falling back 
to PIO\n",
+                               mmc_hostname(mmc));
+                       host->flags &= ~(SDHCI_USE_SDMA | SDHCI_USE_ADMA);
+
+                       ret = 0;
                }
        }
 
-- 
2.7.2