| Message ID | 9c957673-64ba-67ca-46a0-2bde26c95d9c@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2017-01-04 11:33 GMT+01:00 Vladimir Murzin <vladimir.murzin@arm.com>: > Hello Benjamin, > > On 02/01/17 15:26, Benjamin Gaignard wrote: >> Hello Vladimir, >> >> I have tested your patch on my setup (stm32f4: no MMU, no MPU) where >> I'm writing display driver. >> This driver use dma_alloc_wc() and dma_mmap_wc() for frame buffer >> allocation and mmapping. >> >> In dma-mapping-nommu.c you haven't implement dma_map_ops.mmap so >> obviously my driver >> doesn't work with your code. >> In current implementation it is buggy too but I submit a patch to fix >> that problem: >> http://www.armlinux.org.uk/developer/patches/viewpatch.php?id=8633/1 >> >> Could it be possible for you to include mmap support in dma-mapping-nommu.c ? >> > > IIRC, stm32f4 is Cortex-M4, so no cache support and it means that it uses > dma_noop_ops. I offloaded mmap to common implementation, but completely forgot > it has the same restriction as arm counterpart. Regardless, thanks for > noticing that! > > It seems that I need to check that mapping is done from DMA coherent area (I'm > moving to dma-coherent and here we have dma_mmap_from_coherent for that) and > something like bellow for dma_noop_ops: > > diff --git a/lib/dma-noop.c b/lib/dma-noop.c > index 3d766e7..d838b88 100644 > --- a/lib/dma-noop.c > +++ b/lib/dma-noop.c > @@ -64,6 +64,25 @@ static int dma_noop_supported(struct device *dev, u64 mask) > return 1; > } > > +static int dma_noop_mmap(struct device *dev, struct vm_area_struct *vma, > + void *cpu_addr, dma_addr_t dma_addr, size_t size) > +{ > + unsigned long user_count = vma_pages(vma); > + unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; > + unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); > + unsigned long off = vma->vm_pgoff; > + int ret = -ENXIO; > + > + if (off < count && user_count <= (count - off)) { > + ret = remap_pfn_range(vma, vma->vm_start, > + pfn + off, > + user_count << PAGE_SHIFT, > + vma->vm_page_prot); > + } > + > + return ret; > +} > + > struct dma_map_ops dma_noop_ops = { > .alloc = dma_noop_alloc, > .free = dma_noop_free, > @@ -71,6 +90,7 @@ struct dma_map_ops dma_noop_ops = { > .map_sg = dma_noop_map_sg, > .mapping_error = dma_noop_mapping_error, > .dma_supported = dma_noop_supported, > + .mmap = dma_noop_mmap, > }; > > EXPORT_SYMBOL(dma_noop_ops); > > I'd be glad to hear if it works for you. With your patch mmap() does return an address unfortunately framebuffer isn't displayed anymore, I have a black screen instead of the usual pattern. Without your patches my allocations dma_alloc_wc requests go to dma-mapping so I guess the problem is coming from dma noop implementation. I have try to use dma-mapping-nommu ops but the status is the same. > > Cheers > Vladimir > >> Regards, >> Benjamin
On 06/01/17 13:58, Benjamin Gaignard wrote: > 2017-01-04 11:33 GMT+01:00 Vladimir Murzin <vladimir.murzin@arm.com>: >> Hello Benjamin, >> >> On 02/01/17 15:26, Benjamin Gaignard wrote: >>> Hello Vladimir, >>> >>> I have tested your patch on my setup (stm32f4: no MMU, no MPU) where >>> I'm writing display driver. >>> This driver use dma_alloc_wc() and dma_mmap_wc() for frame buffer >>> allocation and mmapping. >>> >>> In dma-mapping-nommu.c you haven't implement dma_map_ops.mmap so >>> obviously my driver >>> doesn't work with your code. >>> In current implementation it is buggy too but I submit a patch to fix >>> that problem: >>> http://www.armlinux.org.uk/developer/patches/viewpatch.php?id=8633/1 >>> >>> Could it be possible for you to include mmap support in dma-mapping-nommu.c ? >>> >> >> IIRC, stm32f4 is Cortex-M4, so no cache support and it means that it uses >> dma_noop_ops. I offloaded mmap to common implementation, but completely forgot >> it has the same restriction as arm counterpart. Regardless, thanks for >> noticing that! >> >> It seems that I need to check that mapping is done from DMA coherent area (I'm >> moving to dma-coherent and here we have dma_mmap_from_coherent for that) and >> something like bellow for dma_noop_ops: >> >> diff --git a/lib/dma-noop.c b/lib/dma-noop.c >> index 3d766e7..d838b88 100644 >> --- a/lib/dma-noop.c >> +++ b/lib/dma-noop.c >> @@ -64,6 +64,25 @@ static int dma_noop_supported(struct device *dev, u64 mask) >> return 1; >> } >> >> +static int dma_noop_mmap(struct device *dev, struct vm_area_struct *vma, >> + void *cpu_addr, dma_addr_t dma_addr, size_t size) >> +{ >> + unsigned long user_count = vma_pages(vma); >> + unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; >> + unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); >> + unsigned long off = vma->vm_pgoff; >> + int ret = -ENXIO; >> + >> + if (off < count && user_count <= (count - off)) { >> + ret = remap_pfn_range(vma, vma->vm_start, >> + pfn + off, >> + user_count << PAGE_SHIFT, >> + vma->vm_page_prot); >> + } >> + >> + return ret; >> +} >> + >> struct dma_map_ops dma_noop_ops = { >> .alloc = dma_noop_alloc, >> .free = dma_noop_free, >> @@ -71,6 +90,7 @@ struct dma_map_ops dma_noop_ops = { >> .map_sg = dma_noop_map_sg, >> .mapping_error = dma_noop_mapping_error, >> .dma_supported = dma_noop_supported, >> + .mmap = dma_noop_mmap, >> }; >> >> EXPORT_SYMBOL(dma_noop_ops); >> >> I'd be glad to hear if it works for you. > > With your patch mmap() does return an address unfortunately > framebuffer isn't displayed > anymore, I have a black screen instead of the usual pattern. > > Without your patches my allocations dma_alloc_wc requests go to > dma-mapping so I guess > the problem is coming from dma noop implementation. > I have try to use dma-mapping-nommu ops but the status is the same. Thanks for giving it a go! I messed up function prototype above, it should be: static int dma_noop_mmap(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size, unsigned long attrs) I've just sent v3 and I tested mmap() there with amba-clcd driver + some hacks to make mmap call work with framebuffer. Cheers Vladimir > >> >> Cheers >> Vladimir >> >>> Regards, >>> Benjamin > > >
diff --git a/lib/dma-noop.c b/lib/dma-noop.c index 3d766e7..d838b88 100644 --- a/lib/dma-noop.c +++ b/lib/dma-noop.c @@ -64,6 +64,25 @@ static int dma_noop_supported(struct device *dev, u64 mask) return 1; } +static int dma_noop_mmap(struct device *dev, struct vm_area_struct *vma, + void *cpu_addr, dma_addr_t dma_addr, size_t size) +{ + unsigned long user_count = vma_pages(vma); + unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; + unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); + unsigned long off = vma->vm_pgoff; + int ret = -ENXIO; + + if (off < count && user_count <= (count - off)) { + ret = remap_pfn_range(vma, vma->vm_start, + pfn + off, + user_count << PAGE_SHIFT, + vma->vm_page_prot); + } + + return ret; +} + struct dma_map_ops dma_noop_ops = { .alloc = dma_noop_alloc, .free = dma_noop_free, @@ -71,6 +90,7 @@ struct dma_map_ops dma_noop_ops = { .map_sg = dma_noop_map_sg, .mapping_error = dma_noop_mapping_error, .dma_supported = dma_noop_supported, + .mmap = dma_noop_mmap, }; EXPORT_SYMBOL(dma_noop_ops);