Hi Felipe,
On Wed, Mar 27, 2013 at 3:17 PM, Felipe Balbi <balbi@xxxxxx> wrote:
> Hi,
>
> On Thu, Mar 14, 2013 at 08:12:09PM +0200, Ruslan Bilovol wrote:
>> MUSB controller cannot work in DMA mode with misaligned buffers,
>> switching in PIO mode.
>>
>> HCD core has hooks that allow to override the default DMA
>> mapping and unmapping routines for host controllers that have
>> special DMA requirements, such as alignment contraints.
>>
>> It is observed that work in PIO mode is slow and it's better
>> to align buffers properly before passing them to MUSB
>>
>> This increased throughput 80->120 MBits/s over musb@omap4 with
>> USB Gigabit ethernet adapter attached.
>>
>> Some ideas taken from ehci-tegra.c
>>
>> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@xxxxxx>
>> ---
>> drivers/usb/musb/musb_core.c | 14 ++++++
>> drivers/usb/musb/musb_host.c | 102 +++++++++++++++++++++++++++++++++++++++++-
>> drivers/usb/musb/musb_host.h | 2 +-
>> 3 files changed, 116 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
>> index 60b41cc..91ac166 100644
>> --- a/drivers/usb/musb/musb_core.c
>> +++ b/drivers/usb/musb/musb_core.c
>> @@ -1431,6 +1431,20 @@ static int musb_core_init(u16 musb_type, struct musb *musb)
>>
>> /* log release info */
>> musb->hwvers = musb_read_hwvers(mbase);
>> +
>> +#ifndef CONFIG_MUSB_PIO_ONLY
>> + /*
>> + * The DMA engine in RTL1.8 and above cannot handle
>> + * DMA addresses that are not aligned to a 4 byte boundary.
>> + * For such engine implemented (un)map_urb_for_dma hooks.
>> + * Do not use these hooks for RTL<1.8
>> + */
>> + if (musb->hwvers < MUSB_HWVERS_1800) {
>
> if you move this check to map/unmap and always return error if this is
> true, you can avoid removing 'const' from our struct hc_driver. Would
> that work ?
If we return an error in map/unmap callbacks, this will break urb transferring,
however I can call core function usb_hcd_(un)map_urb_for_dma() instead of
returning the error (and that is default behavior if we do not have
map/unmap callbacks
set for the hc driver) so I can avoid removing 'const' from our struct
hc_driver and this will work.
The side effect will be only in small overhead for this path.
So, will be this OK for you? I will send v3 in this case.
--
Best regards,
Ruslan Bilvol
>
> --
> balbi
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