Hi Marek, On 6 April 2017 at 04:22, Marek Vasut <[email protected]> wrote: > On 04/06/2017 04:40 AM, Simon Glass wrote: >> Hi Marek, >> >> On 5 April 2017 at 19:32, Marek Vasut <[email protected]> wrote: >>> On 04/06/2017 03:24 AM, Simon Glass wrote: >>>> Hi Marek, >>>> >>>> On 5 April 2017 at 15:34, Marek Vasut <[email protected]> wrote: >>>>> On 04/05/2017 05:03 PM, Simon Glass wrote: >>>>>> +Tom >>>>>> >>>>>> Hi Marek, >>>>>> >>>>>> On 5 April 2017 at 04:21, Marek Vasut <[email protected]> wrote: >>>>>>> On 04/05/2017 12:08 PM, Simon Glass wrote: >>>>>>>> Hi Marek, >>>>>>>> >>>>>>>> On 5 April 2017 at 03:35, Marek Vasut <[email protected]> wrote: >>>>>>>>> On 04/05/2017 04:21 AM, Simon Glass wrote: >>>>>>>>>> Hi, >>>>>>>>>> >>>>>>>>>> On 4 April 2017 at 19:26, Kever Yang <[email protected]> >>>>>>>>>> wrote: >>>>>>>>>>> Hi Eddie, >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> We should only need to do only one time cache operation for a >>>>>>>>>>> buffer >>>>>>>>>>> >>>>>>>>>>> ready to do DMA transfer, so you need to remove another cache >>>>>>>>>>> invalidate >>>>>>>>>>> >>>>>>>>>>> operation for the same buffer in the same function. >>>>>>>>>> >>>>>>>>>> I think this is a more general problem and might cause issues with >>>>>>>>>> other drivers. So I have sent this patch: >>>>>>>>>> >>>>>>>>>> http://patchwork.ozlabs.org/patch/746917/ >>>>>>>>>> >>>>>>>>> >>>>>>>>> This feels like papering over a problem though ... which will bite you >>>>>>>>> later anyway. >>>>>>>> >>>>>>>> I believe the problem only happens because we have cached zero bytes >>>>>>>> caused by this function. If the driver does the right thing (as dwc2.c >>>>>>>> already does) then everything should be find from then on. >>>>>>> >>>>>>> And I think the driver is where this should be fixed ? That is, the >>>>>>> driver should do the right thing and flush/invalidate caches correctly. >>>>>>> >>>>>>>> Notice that the problem does not happen without driver model, since >>>>>>>> non-DM code in dwc2.c uses BSS for the buffers, which is zeroed with >>>>>>>> the cache off. >>>>>> >>>>>> I'm not sure if you read the long and windy thread with Stefan B but >>>>>> the upshot is that the driver is doing the right thing. >>>>>> >>>>>> If the driver were doing the memset() then you could make a case that >>>>>> we should change the driver, but since DM is doing it and DM is >>>>>> promising that DMA can be used on the buffer, I think the best place >>>>>> for the fix is in DM. The driver should not need to change and neither >>>>>> should any other driver when we convert it to DM. >>>>>> >>>>>> On that last point I really want to avoid having to change the caching >>>>>> behaviour of drivers just to work with DM! >>>>> >>>>> So will the driver work with your patch and without DM ? I don't think >>>>> so, so I think what Eddie's patch does is correct. I'd really like him >>>>> to send a new version and apply that. >>>> >>>> Yes the driver work fine without DM and the code is correct. The >>>> buffer is in BSS in that case and we don't have the cache problem. I >>>> think we would have seen this problem before :-) >>> >>> I am seeing problems around this code and this patch makes sense to me, >>> so I think this patch should go in as well ... >> >> OK, well up to you. What sort of problems? > > Some sticks are not detected for me and adding a small delay here > magically fixes it. I suspect I'm hitting this cache issue.
Is this with CONFIG_DM_USB or without? Also does your platform have a write-through or write-back cache? Regards, Simon _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
