Re: [PATCH] Revert "dma-contiguous: do not allocate a single page from CMA area"
On 26/02/2019 20:23, Nicolin Chen wrote: > This reverts commit d222e42e88168fd67e6d131984b86477af1fc256. > > The original change breaks omap dss: > omapdss_dispc 58001000.dispc: > dispc_errata_i734_wa_init: dma_alloc_writecombine failed > > Let's revert it first and then find a safer solution instead. > > Reported-by: Tony Lindgren > Signed-off-by: Nicolin Chen > --- > Tony, > > Would you please test and verify? Thanks! This also fixes various memory allocation failures we have seen on 32-bit Tegra as well. Tested-by: Jon Hunter Cheers Jon -- nvpublic ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH] Revert "dma-contiguous: do not allocate a single page from CMA area"
On Tue, 26 Feb 2019 at 21:25, Nicolin Chen wrote: > > This reverts commit d222e42e88168fd67e6d131984b86477af1fc256. > > The original change breaks omap dss: > omapdss_dispc 58001000.dispc: > dispc_errata_i734_wa_init: dma_alloc_writecombine failed > > Let's revert it first and then find a safer solution instead. > > Reported-by: Tony Lindgren > Signed-off-by: Nicolin Chen > --- > Tony, > > Would you please test and verify? Thanks! > > kernel/dma/contiguous.c | 22 +++--- > 1 file changed, 3 insertions(+), 19 deletions(-) This fixes broken (since yesterday) linux-next on Exynos boards (ARMv7), errors like: dma-pl330: probe of 121a.pdma failed with error -12 exynos-ehci 1211.usb: can't setup: -12 exynos-ehci 1211.usb: USB bus 1 deregistered exynos-ehci 1211.usb: Failed to add USB HCD Tested-by: Krzysztof Kozlowski Best regards, Krzysztof ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH] Revert "dma-contiguous: do not allocate a single page from CMA area"
On Tue, Feb 26, 2019 at 11:35:44PM +, Robin Murphy wrote: > On 2019-02-26 8:23 pm, Nicolin Chen wrote: > > This reverts commit d222e42e88168fd67e6d131984b86477af1fc256. > > > > The original change breaks omap dss: > > omapdss_dispc 58001000.dispc: > > dispc_errata_i734_wa_init: dma_alloc_writecombine failed > > > > Let's revert it first and then find a safer solution instead. > > Ah, I think I see the problem - once arch/arm's __dma_alloc() has decided to > use CMA (because dev_get_cma_area(dev) returns the global area), it then > won't fall back to trying a regular page allocation if > dma_alloc_from_contiguous() returns NULL. Thus anything on 32-bit Arm trying > to allocate a single-page buffer in blockable context with a CMA-enabled > config is just going to fail. Similarly, it looks like none of the > DMA_ATTR_FORCE_CONTIGUOUS cases are prepared to handle this change either > (amd_iommu appears technically affected, but is already using > dma_alloc_from_contiguous() backwards compared to everyone else, hmm). Yea, I searched the tree and got the same results. > I guess the question is whether to add alloc_page()/free_page() fallbacks to > those call sites, or stuff them directly into the CMA helpers here. Probably would be safer/easier to do the later one I feel. ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH] Revert "dma-contiguous: do not allocate a single page from CMA area"
* Robin Murphy [190226 23:36]: > On 2019-02-26 8:23 pm, Nicolin Chen wrote: > > This reverts commit d222e42e88168fd67e6d131984b86477af1fc256. > > > > The original change breaks omap dss: > > omapdss_dispc 58001000.dispc: > > dispc_errata_i734_wa_init: dma_alloc_writecombine failed > > > > Let's revert it first and then find a safer solution instead. Sounds like a good idea since we're only have few days left before the merge window. > Ah, I think I see the problem - once arch/arm's __dma_alloc() has decided to > use CMA (because dev_get_cma_area(dev) returns the global area), it then > won't fall back to trying a regular page allocation if > dma_alloc_from_contiguous() returns NULL. Thus anything on 32-bit Arm trying > to allocate a single-page buffer in blockable context with a CMA-enabled > config is just going to fail. Similarly, it looks like none of the > DMA_ATTR_FORCE_CONTIGUOUS cases are prepared to handle this change either > (amd_iommu appears technically affected, but is already using > dma_alloc_from_contiguous() backwards compared to everyone else, hmm). > > I guess the question is whether to add alloc_page()/free_page() fallbacks to > those call sites, or stuff them directly into the CMA helpers here. Well if you come up with some test patch, I can easily test it :) > > Would you please test and verify? Thanks! Yes this revert works for me: Tested-by: Tony Lindgren ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH] Revert "dma-contiguous: do not allocate a single page from CMA area"
On 2019-02-26 8:23 pm, Nicolin Chen wrote:
This reverts commit d222e42e88168fd67e6d131984b86477af1fc256.
The original change breaks omap dss:
omapdss_dispc 58001000.dispc:
dispc_errata_i734_wa_init: dma_alloc_writecombine failed
Let's revert it first and then find a safer solution instead.
Ah, I think I see the problem - once arch/arm's __dma_alloc() has
decided to use CMA (because dev_get_cma_area(dev) returns the global
area), it then won't fall back to trying a regular page allocation if
dma_alloc_from_contiguous() returns NULL. Thus anything on 32-bit Arm
trying to allocate a single-page buffer in blockable context with a
CMA-enabled config is just going to fail. Similarly, it looks like none
of the DMA_ATTR_FORCE_CONTIGUOUS cases are prepared to handle this
change either (amd_iommu appears technically affected, but is already
using dma_alloc_from_contiguous() backwards compared to everyone else, hmm).
I guess the question is whether to add alloc_page()/free_page()
fallbacks to those call sites, or stuff them directly into the CMA
helpers here.
Robin.
Reported-by: Tony Lindgren
Signed-off-by: Nicolin Chen
---
Tony,
Would you please test and verify? Thanks!
kernel/dma/contiguous.c | 22 +++---
1 file changed, 3 insertions(+), 19 deletions(-)
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 09074bd04793..b2a87905846d 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -186,32 +186,16 @@ int __init dma_contiguous_reserve_area(phys_addr_t size,
phys_addr_t base,
*
* This function allocates memory buffer for specified device. It uses
* device specific contiguous memory area if available or the default
- * global one.
- *
- * However, it skips one-page size of allocations from the global area.
- * As the addresses within one page are always contiguous, so there is
- * no need to waste CMA pages for that kind; it also helps reduce the
- * fragmentations in the CMA area. So a caller should be the rebounder
- * in such case to allocate a normal page upon NULL return value.
- *
- * Requires architecture specific dev_get_cma_area() helper function.
+ * global one. Requires architecture specific dev_get_cma_area() helper
+ * function.
*/
struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
unsigned int align, bool no_warn)
{
- struct cma *cma;
-
if (align > CONFIG_CMA_ALIGNMENT)
align = CONFIG_CMA_ALIGNMENT;
- if (dev && dev->cma_area)
- cma = dev->cma_area;
- else if (count > 1)
- cma = dma_contiguous_default_area;
- else
- return NULL;
-
- return cma_alloc(cma, count, align, no_warn);
+ return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
}
/**
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[PATCH] Revert "dma-contiguous: do not allocate a single page from CMA area"
This reverts commit d222e42e88168fd67e6d131984b86477af1fc256.
The original change breaks omap dss:
omapdss_dispc 58001000.dispc:
dispc_errata_i734_wa_init: dma_alloc_writecombine failed
Let's revert it first and then find a safer solution instead.
Reported-by: Tony Lindgren
Signed-off-by: Nicolin Chen
---
Tony,
Would you please test and verify? Thanks!
kernel/dma/contiguous.c | 22 +++---
1 file changed, 3 insertions(+), 19 deletions(-)
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 09074bd04793..b2a87905846d 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -186,32 +186,16 @@ int __init dma_contiguous_reserve_area(phys_addr_t size,
phys_addr_t base,
*
* This function allocates memory buffer for specified device. It uses
* device specific contiguous memory area if available or the default
- * global one.
- *
- * However, it skips one-page size of allocations from the global area.
- * As the addresses within one page are always contiguous, so there is
- * no need to waste CMA pages for that kind; it also helps reduce the
- * fragmentations in the CMA area. So a caller should be the rebounder
- * in such case to allocate a normal page upon NULL return value.
- *
- * Requires architecture specific dev_get_cma_area() helper function.
+ * global one. Requires architecture specific dev_get_cma_area() helper
+ * function.
*/
struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
unsigned int align, bool no_warn)
{
- struct cma *cma;
-
if (align > CONFIG_CMA_ALIGNMENT)
align = CONFIG_CMA_ALIGNMENT;
- if (dev && dev->cma_area)
- cma = dev->cma_area;
- else if (count > 1)
- cma = dma_contiguous_default_area;
- else
- return NULL;
-
- return cma_alloc(cma, count, align, no_warn);
+ return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
}
/**
--
2.17.1
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