[U-Boot] [PATCH] dwc: ep0: Allocate and flush dwc->ep0_trb in a cache aligned manner

[Kishon Vijay Abraham I]

Hi,

On Tuesday 10 October 2017 11:07 AM, Faiz Abbas wrote:
> +Kishon
> 
> On Friday 06 October 2017 05:03 PM, Faiz Abbas wrote:
>> Hi,
>>
>> On Thursday 05 October 2017 04:57 PM, Marek Vasut wrote:
>>> On 10/04/2017 03:11 PM, Faiz Abbas wrote:
>>>> Hi,
>>>>
>>>> On Wednesday 04 October 2017 06:01 PM, Marek Vasut wrote:
>>>>> On 10/04/2017 12:51 PM, Faiz Abbas wrote:
>>>>>> Hi,
>>>>>> On Tuesday 03 October 2017 06:48 PM, Marek Vasut wrote:
>>>>>>> On 10/03/2017 03:17 PM, Faiz Abbas wrote:
>>>>>>>> Hi,
>>>>>>>> On Tuesday 03 October 2017 05:34 PM, Marek Vasut wrote:
>>>>>>>>> On 09/19/2017 01:15 PM, Faiz Abbas wrote:
>>>>>>>>>>  
>>>>>>>>>> -	dwc3_flush_cache((uintptr_t)trb, sizeof(*trb));
>>>>>>>>>> +	dwc3_flush_cache((uintptr_t)dwc->ep0_trb_addr, sizeof(*trb) * 2);
>>>>>>>>>
>>>>>>>>> Why *2 ?
>>>>>>>>
>>>>>>>> Because its allocated as sizeof(*dwc->ep0_trb) * 2 below. This is not
>>>>>>>> strictly required as dwc3_flush_cache() rounds up the size to
>>>>>>>> CACHELINE_SIZE but from a caller POV, flush everything we allocated.
>>>>>>>
>>>>>>> Can the other TRB be in use ? Maybe aligning the TRBs to cacheline size
>>>>>>> would be better ?
>>>>>>>
>>>>>> A single trb is 16 bytes in size and two of them are allocated
>>>>>> contiguously.
>>>>>
>>>>> Why are two allocated continuously ? (I am not dwc3 expert)

The TRB's should be allocated contiguously for dwc3 and only the base of the
entire TRB table is programmed in the HW.
 ________________ <------------------ TRB table base address
|     TRB0       |
|________________|
|     TRB1       |
|________________|
|     TRB2       |
|________________|
|     TRBn       |
|________________|


>>>>
>>>> Neither am I. I did try to pad to the dwc_trb structure such that each
>>>> trb is 64 bytes in size but this leads to failures when testing. I
>>>> didn't get a chance to debug this though. I suspect its because the code
>>>> expects the trbs to be contiguous and/or 16 bytes in size.

It's not the code but it's the HW.

Thanks
Kishon