Hi,
On Thu, Feb 23, 2012 at 6:25 AM, Puneet Saxena <pune...@nvidia.com> wrote:
> As DMA expects the buffers to be equal and larger then
> cache lines, This aligns buffers at cacheline.
>
> Signed-off-by: Puneet Saxena <pune...@nvidia.com>
> Signed-off-by: Jim Lin <ji...@nvidia.com>
> ---
> Changes for v2:
> - Split the commit in to 2 commits
> - "ARCH_DMA_MINALIGN" replacement
> - Making stop address cache line aligned by
> making size as multiple of cache line
> - incorporated Marek and Mike's comment
>
> common/cmd_usb.c | 3 +-
> common/usb.c | 53 ++++++++++++++++++----------------
> common/usb_storage.c | 66 ++++++++++++++++++++++--------------------
> drivers/usb/host/ehci-hcd.c | 9 ++++++
> include/scsi.h | 8 ++++-
> include/usb.h | 8 ++++-
> 6 files changed, 88 insertions(+), 59 deletions(-)
> diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
> index d893b2a..82652f5 100644
> --- a/drivers/usb/host/ehci-hcd.c
> +++ b/drivers/usb/host/ehci-hcd.c
> @@ -120,6 +120,15 @@ static struct descriptor {
> */
> static void flush_invalidate(u32 addr, int size, int flush)
> {
> + /*
> + * Size is the bytes actually moved during transaction,
> + * which may not equal to the cache line. This results
> + * stop address passed for invalidating cache may not be aligned.
> + * Therfore making size as nultiple of cache line size.
> + */
> + if (size & (ARCH_DMA_MINALIGN - 1))
> + size = ((size / ARCH_DMA_MINALIGN) + 1)
> + * ARCH_DMA_MINALIGN;
Can we just use:
size = ALIGN(size, ARCH_DMA_MINALIGN)
here or does it increase size even if already aligned?
> if (flush)
> flush_dcache_range(addr, addr + size);
> else
> diff --git a/include/scsi.h b/include/scsi.h
> index c52759c..c1f573e 100644
> --- a/include/scsi.h
> +++ b/include/scsi.h
> @@ -26,7 +26,13 @@
>
> typedef struct SCSI_cmd_block{
> unsigned char cmd[16];
> /* command */
> - unsigned char sense_buf[64]; /* for request sense
> */
> + /* for request sense */
> +#ifdef ARCH_DMA_MINALIGN
> + unsigned char sense_buf[64]
> + __attribute__((aligned(ARCH_DMA_MINALIGN)));
> +#else
> + unsigned char sense_buf[64];
> +#endif
I think Mike said this, but I thought ARCH_DMA_MINALIGN should always
be defined.
Is it possible to align something in the middle of a structure? How
does that work? I'm suppose you have this working, I would just like
to understand what the resulting code does in this case.
> unsigned char status;
> /* SCSI Status */
> unsigned char target;
> /* Target ID */
> unsigned char lun;
> /* Target LUN */
> diff --git a/include/usb.h b/include/usb.h
> index 06170cd..d38817a 100644
> --- a/include/usb.h
> +++ b/include/usb.h
> @@ -109,7 +109,13 @@ struct usb_device {
> int epmaxpacketout[16]; /* OUTput endpoint specific maximums */
>
> int configno; /* selected config number */
> - struct usb_device_descriptor descriptor; /* Device Descriptor */
> + /* Device Descriptor */
> +#ifdef ARCH_DMA_MINALIGN
> + struct usb_device_descriptor descriptor
> + __attribute__((aligned(ARCH_DMA_MINALIGN)));
> +#else
> + struct usb_device_descriptor descriptor;
> +#endif
Same question here, it seems even more exotic - maybe you will need a
memcpy somewhere after all?
> struct usb_config config; /* config descriptor */
>
> int have_langid; /* whether string_langid is valid yet
> */
> --
> 1.7.1
>
Regards,
Simon
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