Re: [PATCH 5/5] dma-mapping: remove ARCH_NO_COHERENT_DMA_MMAP
From: Takashi Iwai
Date: Fri Aug 02 2019 - 04:24:03 EST
On Fri, 02 Aug 2019 09:03:54 +0200,
Christoph Hellwig wrote:
>
> Takashi,
>
> any comments on the sounds/ side of this?
I wasn't careful enough to look at that change, sorry.
The code there tries to check whether dma_mmap_coherent() would always
fail on some platforms. Then the driver clears the mmap capability
flag at the device open time and notifies user-space to fall back to
the dumb read/write mode.
So I'm afraid that simply dropping the check would cause the behavior
regression, e.g. on PARISC.
Is there any simple way to test whether dma_mmap_coherent() would work
or not in general on the target platform? It's not necessarily in an
ifdef at all.
thanks,
Takashi
> On Thu, Jul 25, 2019 at 08:34:01AM +0200, Christoph Hellwig wrote:
> > Now that we never use a default ->mmap implementation, and non-coherent
> > architectures can control the presence of ->mmap support by enabling
> > ARCH_HAS_DMA_COHERENT_TO_PFN for the dma direct implementation there
> > is no need for a global config option to control the availability
> > of dma_common_mmap.
> >
> > Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> > ---
> > arch/Kconfig | 3 ---
> > arch/c6x/Kconfig | 1 -
> > arch/m68k/Kconfig | 1 -
> > arch/microblaze/Kconfig | 1 -
> > arch/parisc/Kconfig | 1 -
> > arch/sh/Kconfig | 1 -
> > arch/xtensa/Kconfig | 1 -
> > kernel/dma/mapping.c | 4 ----
> > sound/core/pcm_native.c | 10 +---------
> > 9 files changed, 1 insertion(+), 22 deletions(-)
> >
> > diff --git a/arch/Kconfig b/arch/Kconfig
> > index a7b57dd42c26..ec2834206d08 100644
> > --- a/arch/Kconfig
> > +++ b/arch/Kconfig
> > @@ -790,9 +790,6 @@ config COMPAT_32BIT_TIME
> > This is relevant on all 32-bit architectures, and 64-bit architectures
> > as part of compat syscall handling.
> >
> > -config ARCH_NO_COHERENT_DMA_MMAP
> > - bool
> > -
> > config ARCH_NO_PREEMPT
> > bool
> >
> > diff --git a/arch/c6x/Kconfig b/arch/c6x/Kconfig
> > index b4fb61c83494..e65e8d82442a 100644
> > --- a/arch/c6x/Kconfig
> > +++ b/arch/c6x/Kconfig
> > @@ -20,7 +20,6 @@ config C6X
> > select OF_EARLY_FLATTREE
> > select GENERIC_CLOCKEVENTS
> > select MODULES_USE_ELF_RELA
> > - select ARCH_NO_COHERENT_DMA_MMAP
> > select MMU_GATHER_NO_RANGE if MMU
> >
> > config MMU
> > diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
> > index c518d695c376..614b355ae338 100644
> > --- a/arch/m68k/Kconfig
> > +++ b/arch/m68k/Kconfig
> > @@ -8,7 +8,6 @@ config M68K
> > select ARCH_HAS_DMA_PREP_COHERENT if HAS_DMA && MMU && !COLDFIRE
> > select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA
> > select ARCH_MIGHT_HAVE_PC_PARPORT if ISA
> > - select ARCH_NO_COHERENT_DMA_MMAP if !MMU
> > select ARCH_NO_PREEMPT if !COLDFIRE
> > select BINFMT_FLAT_ARGVP_ENVP_ON_STACK
> > select DMA_DIRECT_REMAP if HAS_DMA && MMU && !COLDFIRE
> > diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
> > index d411de05b628..632c9477a0f6 100644
> > --- a/arch/microblaze/Kconfig
> > +++ b/arch/microblaze/Kconfig
> > @@ -9,7 +9,6 @@ config MICROBLAZE
> > select ARCH_HAS_SYNC_DMA_FOR_CPU
> > select ARCH_HAS_SYNC_DMA_FOR_DEVICE
> > select ARCH_MIGHT_HAVE_PC_PARPORT
> > - select ARCH_NO_COHERENT_DMA_MMAP if !MMU
> > select ARCH_WANT_IPC_PARSE_VERSION
> > select BUILDTIME_EXTABLE_SORT
> > select TIMER_OF
> > diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
> > index 6d732e451071..e9dd88b7f81e 100644
> > --- a/arch/parisc/Kconfig
> > +++ b/arch/parisc/Kconfig
> > @@ -52,7 +52,6 @@ config PARISC
> > select GENERIC_SCHED_CLOCK
> > select HAVE_UNSTABLE_SCHED_CLOCK if SMP
> > select GENERIC_CLOCKEVENTS
> > - select ARCH_NO_COHERENT_DMA_MMAP
> > select CPU_NO_EFFICIENT_FFS
> > select NEED_DMA_MAP_STATE
> > select NEED_SG_DMA_LENGTH
> > diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> > index 6b1b5941b618..f356ee674d89 100644
> > --- a/arch/sh/Kconfig
> > +++ b/arch/sh/Kconfig
> > @@ -5,7 +5,6 @@ config SUPERH
> > select ARCH_HAS_PTE_SPECIAL
> > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> > select ARCH_MIGHT_HAVE_PC_PARPORT
> > - select ARCH_NO_COHERENT_DMA_MMAP if !MMU
> > select HAVE_PATA_PLATFORM
> > select CLKDEV_LOOKUP
> > select DMA_DECLARE_COHERENT
> > diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
> > index ebc135bda921..70653aed3005 100644
> > --- a/arch/xtensa/Kconfig
> > +++ b/arch/xtensa/Kconfig
> > @@ -5,7 +5,6 @@ config XTENSA
> > select ARCH_HAS_BINFMT_FLAT if !MMU
> > select ARCH_HAS_SYNC_DMA_FOR_CPU
> > select ARCH_HAS_SYNC_DMA_FOR_DEVICE
> > - select ARCH_NO_COHERENT_DMA_MMAP if !MMU
> > select ARCH_USE_QUEUED_RWLOCKS
> > select ARCH_USE_QUEUED_SPINLOCKS
> > select ARCH_WANT_FRAME_POINTERS
> > diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
> > index 7dff1829c8c5..815446f76995 100644
> > --- a/kernel/dma/mapping.c
> > +++ b/kernel/dma/mapping.c
> > @@ -169,7 +169,6 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> > void *cpu_addr, dma_addr_t dma_addr, size_t size,
> > unsigned long attrs)
> > {
> > -#ifndef CONFIG_ARCH_NO_COHERENT_DMA_MMAP
> > unsigned long user_count = vma_pages(vma);
> > unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> > unsigned long off = vma->vm_pgoff;
> > @@ -198,9 +197,6 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> >
> > return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
> > user_count << PAGE_SHIFT, vma->vm_page_prot);
> > -#else
> > - return -ENXIO;
> > -#endif /* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */
> > }
> >
> > /**
> > diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> > index 860543a4c840..2dadc708343a 100644
> > --- a/sound/core/pcm_native.c
> > +++ b/sound/core/pcm_native.c
> > @@ -218,15 +218,7 @@ int snd_pcm_info_user(struct snd_pcm_substream *substream,
> >
> > static bool hw_support_mmap(struct snd_pcm_substream *substream)
> > {
> > - if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP))
> > - return false;
> > - /* architecture supports dma_mmap_coherent()? */
> > -#if defined(CONFIG_ARCH_NO_COHERENT_DMA_MMAP) || !defined(CONFIG_HAS_DMA)
> > - if (!substream->ops->mmap &&
> > - substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV)
> > - return false;
> > -#endif
> > - return true;
> > + return substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP;
> > }
> >
> > static int constrain_mask_params(struct snd_pcm_substream *substream,
> > --
> > 2.20.1
> >
> >
> > _______________________________________________
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> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> ---end quoted text---
>