On 04/06/2017 04:06 PM, Simon Glass wrote: > 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?
With. > Also does your platform have a write-through or write-back cache? I think WT, but I'm not 100% sure . I can check when I have access to the board . It's SoCFPGA, C-A9 . -- Best regards, Marek Vasut _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
