On 08/01/2020 8:28 am, Peter Ujfalusi via iommu wrote:

Hi Christoph,

On 19/12/2019 17.20, Peter Ujfalusi wrote:

quoted

Hi Christoph,

On 19/12/2019 17.02, Christoph Hellwig wrote:

quoted

Hi Peter,

can you try the patch below (it will need to be split into two):

Thank you!

Unfortunately it does not help:
[    0.596208] edma: probe of 2700000.edma failed with error -5
[    0.596626] edma: probe of 2728000.edma failed with error -5
...
[    2.108602] sdhci-omap 23000000.mmc: Got CD GPIO
[    2.113899] mmc0: Failed to set 32-bit DMA mask.
[    2.118592] mmc0: No suitable DMA available - falling back to PIO
[    2.159038] mmc0: SDHCI controller on 23000000.mmc [23000000.mmc]
using PIO
[    2.167531] mmc1: Failed to set 32-bit DMA mask.
[    2.172192] mmc1: No suitable DMA available - falling back to PIO
[    2.213841] mmc1: SDHCI controller on 23100000.mmc [23100000.mmc]
using PIO

Do you have idea on how to fix this in a proper way?

IMHO when drivers are setting the dma_mask and coherent_mask the
dma_pfn_offset should not be applied to the mask at all.

If I understand it correctly for EDMA as example:

I set dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
since it can only address memory in this range.

It does not matter if dma_pfn_offset is 0 or not 0 (like in k2g, where
it is 0x780000) the EDMA still can only address within 32 bits.

The dma_pfn_offset will tell us that the memory location's physical
address is seen by the DMA at (phys_pfn - dma_pfn_offset) -> dma_pfn.

The dma_mask should be checked against the dma_pfn.

That's exactly what dma_direct_supported() does, though. What it doesn't 
do, AFAICS, is account for weird cases where the DMA zone *starts* way, 
way above 32 physical address bits because of an implicit assumption 
that *all* devices have a dma_pfn_offset equal to min_low_pfn. I'm not 
sure how possible it is to cope with that generically.

Robin.

We can not 'move' the dma_mask with dma_pfn_offset when setting the mask
since it is not correct. The DMA can access in 32 bits range and we have
the peripherals under 0x8000 0000.

I might be missing something, but it looks to me that the way we set the
dma_mask and the coherent_mask is the place where this can be fixed.

Best regards,
- Péter

quoted

- Péter

quoted

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index e822af0d9219..30b9c6786ce3 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c

@@ -221,7 +221,8 @@ EXPORT_SYMBOL(arm_coherent_dma_ops);
  
  static int __dma_supported(struct device *dev, u64 mask, bool warn)
  {
-	unsigned long max_dma_pfn = min(max_pfn, arm_dma_pfn_limit);
+	unsigned long max_dma_pfn =
+		min_t(unsigned long, max_pfn, zone_dma_limit >> PAGE_SHIFT);
  
  	/*
  	 * Translate the device's DMA mask to a PFN limit.  This

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 3ef204137e73..dd0e169a1bb1 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c

@@ -19,6 +19,7 @@
  #include <linux/gfp.h>
  #include <linux/memblock.h>
  #include <linux/dma-contiguous.h>
+#include <linux/dma-direct.h>
  #include <linux/sizes.h>
  #include <linux/stop_machine.h>
  #include <linux/swiotlb.h>

@@ -84,15 +85,6 @@ static void __init find_limits(unsigned long *min, unsigned long *max_low,
  phys_addr_t arm_dma_zone_size __read_mostly;
  EXPORT_SYMBOL(arm_dma_zone_size);
  
-/*
- * The DMA mask corresponding to the maximum bus address allocatable
- * using GFP_DMA.  The default here places no restriction on DMA
- * allocations.  This must be the smallest DMA mask in the system,
- * so a successful GFP_DMA allocation will always satisfy this.
- */
-phys_addr_t arm_dma_limit;
-unsigned long arm_dma_pfn_limit;
-
  static void __init arm_adjust_dma_zone(unsigned long *size, unsigned long *hole,
  	unsigned long dma_size)
  {

@@ -108,14 +100,14 @@ static void __init arm_adjust_dma_zone(unsigned long *size, unsigned long *hole,
  
  void __init setup_dma_zone(const struct machine_desc *mdesc)
  {
-#ifdef CONFIG_ZONE_DMA
-	if (mdesc->dma_zone_size) {
+	if (!IS_ENABLED(CONFIG_ZONE_DMA)) {
+		zone_dma_limit = ((phys_addr_t)~0);
+	} else if (mdesc->dma_zone_size) {
  		arm_dma_zone_size = mdesc->dma_zone_size;
-		arm_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1;
-	} else
-		arm_dma_limit = 0xffffffff;
-	arm_dma_pfn_limit = arm_dma_limit >> PAGE_SHIFT;
-#endif
+		zone_dma_limit = PHYS_OFFSET + arm_dma_zone_size - 1;
+	} else {
+		zone_dma_limit = 0xffffffff;
+	}
  }
  
  static void __init zone_sizes_init(unsigned long min, unsigned long max_low,

@@ -279,7 +271,7 @@ void __init arm_memblock_init(const struct machine_desc *mdesc)
  	early_init_fdt_scan_reserved_mem();
  
  	/* reserve memory for DMA contiguous allocations */
-	dma_contiguous_reserve(arm_dma_limit);
+	dma_contiguous_reserve(zone_dma_limit);
  
  	arm_memblock_steal_permitted = false;
  	memblock_dump_all();

diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
index 88c121ac14b3..7dbd77554273 100644
--- a/arch/arm/mm/mm.h
+++ b/arch/arm/mm/mm.h

@@ -82,14 +82,6 @@ extern __init void add_static_vm_early(struct static_vm *svm);
  
  #endif
  
-#ifdef CONFIG_ZONE_DMA
-extern phys_addr_t arm_dma_limit;
-extern unsigned long arm_dma_pfn_limit;
-#else
-#define arm_dma_limit ((phys_addr_t)~0)
-#define arm_dma_pfn_limit (~0ul >> PAGE_SHIFT)
-#endif
-
  extern phys_addr_t arm_lowmem_limit;
  
  void __init bootmem_init(void);

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index b65dffdfb201..7a7501acd763 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -441,7 +441,7 @@ void __init arm64_memblock_init(void)
  	early_init_fdt_scan_reserved_mem();
  
  	if (IS_ENABLED(CONFIG_ZONE_DMA)) {
-		zone_dma_bits = ARM64_ZONE_DMA_BITS;
+		zone_dma_limit = DMA_BIT_MASK(ARM64_ZONE_DMA_BITS);
  		arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS);
  	}
  

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9488b63dfc87..337ace03d3f0 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c

@@ -223,7 +223,7 @@ static int __init mark_nonram_nosave(void)
   * everything else. GFP_DMA32 page allocations automatically fall back to
   * ZONE_DMA.
   *
- * By using 31-bit unconditionally, we can exploit zone_dma_bits to inform the
+ * By using 31-bit unconditionally, we can exploit zone_dma_limit to inform the
   * generic DMA mapping code.  32-bit only devices (if not handled by an IOMMU
   * anyway) will take a first dip into ZONE_NORMAL and get otherwise served by
   * ZONE_DMA.

@@ -257,18 +257,20 @@ void __init paging_init(void)
  	printk(KERN_DEBUG "Memory hole size: %ldMB\n",
  	       (long int)((top_of_ram - total_ram) >> 20));
  
+#ifdef CONFIG_ZONE_DMA
  	/*
  	 * Allow 30-bit DMA for very limited Broadcom wifi chips on many
  	 * powerbooks.
  	 */
-	if (IS_ENABLED(CONFIG_PPC32))
-		zone_dma_bits = 30;
-	else
-		zone_dma_bits = 31;
-
-#ifdef CONFIG_ZONE_DMA
-	max_zone_pfns[ZONE_DMA]	= min(max_low_pfn,
-				      1UL << (zone_dma_bits - PAGE_SHIFT));
+	if (IS_ENABLED(CONFIG_PPC32)) {
+		zone_dma_limit = DMA_BIT_MASK(30);
+		max_zone_pfns[ZONE_DMA]	= min(max_low_pfn,
+					      1UL << (30 - PAGE_SHIFT));
+	} else {
+		zone_dma_limit = DMA_BIT_MASK(31);
+		max_zone_pfns[ZONE_DMA]	= min(max_low_pfn,
+					      1UL << (31 - PAGE_SHIFT));
+	}
  #endif
  	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
  #ifdef CONFIG_HIGHMEM

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index f0ce22220565..c403f61cb56b 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c

@@ -118,7 +118,7 @@ void __init paging_init(void)
  
  	sparse_memory_present_with_active_regions(MAX_NUMNODES);
  	sparse_init();
-	zone_dma_bits = 31;
+	zone_dma_limit = DMA_BIT_MASK(31);
  	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
  	max_zone_pfns[ZONE_DMA] = PFN_DOWN(MAX_DMA_ADDRESS);
  	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;

diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 24b8684aa21d..20d56d597506 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h

@@ -6,7 +6,7 @@
  #include <linux/memblock.h> /* for min_low_pfn */
  #include <linux/mem_encrypt.h>
  
-extern unsigned int zone_dma_bits;
+extern phys_addr_t zone_dma_limit;
  
  #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
  #include <asm/dma-direct.h>

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 6af7ae83c4ad..5ea1bed2ba6f 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c

@@ -21,7 +21,7 @@
   * it for entirely different regions. In that case the arch code needs to
   * override the variable below for dma-direct to work properly.
   */
-unsigned int zone_dma_bits __ro_after_init = 24;
+phys_addr_t zone_dma_limit __ro_after_init = DMA_BIT_MASK(24);
  
  static void report_addr(struct device *dev, dma_addr_t dma_addr, size_t size)
  {

@@ -74,7 +74,7 @@ static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
  	 * Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
  	 * zones.
  	 */
-	if (*phys_limit <= DMA_BIT_MASK(zone_dma_bits))
+	if (*phys_limit <= zone_dma_limit)
  		return GFP_DMA;
  	if (*phys_limit <= DMA_BIT_MASK(32))
  		return GFP_DMA32;

@@ -483,7 +483,7 @@ int dma_direct_supported(struct device *dev, u64 mask)
  	u64 min_mask;
  
  	if (IS_ENABLED(CONFIG_ZONE_DMA))
-		min_mask = DMA_BIT_MASK(zone_dma_bits);
+		min_mask = zone_dma_limit;
  	else
  		min_mask = DMA_BIT_MASK(32);
  

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