Re: [PATCH v2 2/2] dma-contiguous: Use fallback alloc_pages for single pages
From: Masahiro Yamada <hidden>
Date: 2019-08-27 09:04:12
Also in:
linux-iommu, linux-mmc, lkml
Subsystem:
multimedia card (mmc), secure digital (sd) and sdio subsystem, secure digital host controller interface (sdhci) driver, the rest · Maintainers:
Ulf Hansson, Adrian Hunter, Linus Torvalds
On Tue, Aug 27, 2019 at 4:50 PM Christoph Hellwig [off-list ref] wrote:
On Tue, Aug 27, 2019 at 04:45:20PM +0900, Masahiro Yamada wrote:quoted
On Mon, Aug 26, 2019 at 4:33 PM Christoph Hellwig [off-list ref] wrote:quoted
On Mon, Aug 26, 2019 at 11:05:00AM +0900, Masahiro Yamada wrote:quoted
This is included in v5.3-rc6 so I tested it.So there is no allocation failure, but you get I/O errors later?Right.quoted
Does the device use a device-private CMA area?Not sure. My driver is drivers/mmc/host/sdhci-cadence.c It reuses routines in drivers/mmc/host/sdhci.cquoted
Does it work with Linux 5.2 if CONFIG_DMA_CMA is disabled?No. 5.2 + disable CONFIG_DMA_CMA failed in the same way.So it seems like the device wants CMA memory. I guess the patch below will fix it, but that isn't the solution. Can you try it to confirm? In the end it probably assumes a dma mask it doesn't set that the CMA memory satisfies or something similar.
Thanks for the pointer.
quoted hunk ↗ jump to hunk
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 69cfb4345388..bd2f24aa7f19 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c@@ -236,7 +236,7 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) if (dev && dev->cma_area) cma = dev->cma_area; - else if (count > 1) + else cma = dma_contiguous_default_area; /* CMA can be used only in the context which permits sleeping */
Yes, this makes my driver working again when CONFIG_DMA_CMA=y. If I apply the following, my driver gets back working irrespective of CONFIG_DMA_CMA.
diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
index 163d1cf4367e..504459395c39 100644
--- a/drivers/mmc/host/sdhci-cadence.c
+++ b/drivers/mmc/host/sdhci-cadence.c@@ -237,6 +237,7 @@ static const struct sdhci_ops sdhci_cdns_ops = { static const struct sdhci_pltfm_data sdhci_cdns_pltfm_data = { .ops = &sdhci_cdns_ops, + .quirks2 = SDHCI_QUIRK2_BROKEN_64_BIT_DMA, }; static int sdhci_cdns_set_tune_val(struct sdhci_host *host, unsigned int val)
--
Best Regards
Masahiro Yamada
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