> + u64 dma_mask = dma_get_mask(dev); This is not a driver API. I think what you want is dma_get_required_mask to query the mask. But in that case you still need to always actually set a mask in the driver as well. Something like this patch: diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index a22e11a65658..36c61778d8f3 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -3500,6 +3500,13 @@ static int sdhci_set_dma_mask(struct sdhci_host *host) struct device *dev = mmc_dev(mmc); int ret = -EINVAL; + /* + * Systems that can't address more than 32-bits do not need to use + * 64-bit addressing mode, even if the device supports it. + */ + if (dma_get_required_mask(dev) <= DMA_BIT_MASK(32)) + host->flags &= ~SDHCI_USE_64_BIT_DMA; + if (host->quirks2 & SDHCI_QUIRK2_BROKEN_64_BIT_DMA) host->flags &= ~SDHCI_USE_64_BIT_DMA;
