On 07/03/16 04:07, Alexandre Courbot wrote:
> 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));
What happens if device enumeration (e.g. of_dma_configure) has already set a
more restrictive DMA mask?
> + 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;
> }
> }
>
>
