Hi Kumar, On 21 October 2014 12:08, Kumar Gala <ga...@codeaurora.org> wrote: > > On Oct 21, 2014, at 7:56 AM, Ankit Jindal <ankit.jin...@linaro.org> wrote: > >> Currently, three types of mem regions are supported: UIO_MEM_PHYS, >> UIO_MEM_LOGICAL and UIO_MEM_VIRTUAL. Among these UIO_MEM_PHYS helps >> UIO driver export physcial memory to user space as non-cacheable >> user memory. Typcially memory-mapped registers of a device are exported >> to user space as UIO_MEM_PHYS type mem region. The UIO_MEM_PHYS type >> is not efficient if dma-capable devices are capable of maintaining coherency >> with CPU caches. >> >> This patch adds new type UIO_MEM_PHYS_CACHE for mem regions to enable >> cacheable access to physical memory from user space. >> >> Signed-off-by: Ankit Jindal <ankit.jin...@linaro.org> >> Signed-off-by: Tushar Jagad <tushar.ja...@linaro.org> >> --- >> drivers/uio/uio.c | 11 ++++++++--- >> include/linux/uio_driver.h | 1 + >> 2 files changed, 9 insertions(+), 3 deletions(-) > > Rather than adding a new type, why not allow the driver to set the pgprot > value, this way one has full control and we don’t need to keep adding types > for various different cache attributions in the future.
Do you mean to add a new field pgprot_t in the memtype structure and uio_mmap_physical will set vma->vm_page_prot to this value provided by driver ? If this is the case then we will need to change all the current uio based drivers which was the reason I preferred to have a new mem type. Please let me know if I have misunderstood anything. Thanks, Ankit > > - k > >> >> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c >> index 97e6444..120a84b 100644 >> --- a/drivers/uio/uio.c >> +++ b/drivers/uio/uio.c >> @@ -644,7 +644,7 @@ static const struct vm_operations_struct >> uio_physical_vm_ops = { >> #endif >> }; >> >> -static int uio_mmap_physical(struct vm_area_struct *vma) >> +static int uio_mmap_physical(struct vm_area_struct *vma, bool cacheable) >> { >> struct uio_device *idev = vma->vm_private_data; >> int mi = uio_find_mem_index(vma); >> @@ -659,7 +659,9 @@ static int uio_mmap_physical(struct vm_area_struct *vma) >> return -EINVAL; >> >> vma->vm_ops = &uio_physical_vm_ops; >> - vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); >> + >> + if (!cacheable) >> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); >> >> /* >> * We cannot use the vm_iomap_memory() helper here, >> @@ -707,10 +709,13 @@ static int uio_mmap(struct file *filep, struct >> vm_area_struct *vma) >> >> switch (idev->info->mem[mi].memtype) { >> case UIO_MEM_PHYS: >> - return uio_mmap_physical(vma); >> + return uio_mmap_physical(vma, false); >> case UIO_MEM_LOGICAL: >> case UIO_MEM_VIRTUAL: >> return uio_mmap_logical(vma); >> + case UIO_MEM_PHYS_CACHE: >> + return uio_mmap_physical(vma, true); >> + >> default: >> return -EINVAL; >> } >> diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h >> index 1ad4724..40ca3f3 100644 >> --- a/include/linux/uio_driver.h >> +++ b/include/linux/uio_driver.h >> @@ -118,6 +118,7 @@ extern void uio_event_notify(struct uio_info *info); >> #define UIO_MEM_PHYS 1 >> #define UIO_MEM_LOGICAL 2 >> #define UIO_MEM_VIRTUAL 3 >> +#define UIO_MEM_PHYS_CACHE 4 >> >> /* defines for uio_port->porttype */ >> #define UIO_PORT_NONE 0 >> -- >> 1.7.9.5 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe devicetree" in >> the body of a message to majord...@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/