Messages in this thread | | | Date | Fri, 6 Mar 2020 15:29:12 +0200 | From | Andy Shevchenko <> | Subject | Re: [PATCH 0/5] dmaengine: dw: Take Baikal-T1 SoC DW DMAC peculiarities into account |
| |
On Fri, Mar 06, 2020 at 04:10:29PM +0300, Sergey.Semin@baikalelectronics.ru wrote: > From: Serge Semin <fancer.lancer@gmail.com> > > Baikal-T1 SoC has an DW DMAC on-board to provide a Mem-to-Mem, low-speed > peripherals Dev-to-Mem and Mem-to-Dev functionality. Mostly it's compatible > with currently implemented in the kernel DW DMAC driver, but there are some > peculiarities which must be taken into account in order to have the device > fully supported. > > First of all traditionally we replaced the legacy plain text-based dt-binding > file with yaml-based one. Secondly Baikal-T1 DW DMA Controller provides eight > channels, which alas have different max burst length configuration. > In particular first two channels may burst up to 128 bits (16 bytes) at a time > while the rest of them just up to 32 bits. We must make sure that the DMA > subsystem doesn't set values exceeding these limitations otherwise the > controller will hang up. In third currently we discovered the problem in using > the DW APB SPI driver together with DW DMAC. The problem happens if there is no > natively implemented multi-block LLP transfers support and the SPI-transfer > length exceeds the max lock size. In this case due to asynchronous handling of > Tx- and Rx- SPI transfers interrupt we might end up with Dw APB SSI Rx FIFO > overflow. So if DW APB SSI (or any other DMAC service consumer) intends to use > the DMAC to asynchronously execute the transfers we'd have to at least warn > the user of the possible errors. > > Finally there is a bug in the algorithm of the nollp flag detection. > In particular even if DW DMAC parameters state the multi-block transfers > support there is still HC_LLP (hardcode LLP) flag, which if set makes expected > by the driver true multi-block LLP functionality unusable. This happens cause' > if HC_LLP flag is set the LLP registers will be hardcoded to zero so the > contiguous multi-block transfers will be only supported. We must take the > flag into account when detecting the LLP support otherwise the driver just > won't work correctly. > > This patchset is rebased and tested on the mainline Linux kernel 5.6-rc4: > commit 98d54f81e36b ("Linux 5.6-rc4").
Thank you for your series!
I'll definitely review it, but it will take time. So, I think due to late submission this is material at least for v5.8.
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> > Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru> > Cc: Maxim Kaurkin <Maxim.Kaurkin@baikalelectronics.ru> > Cc: Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru> > Cc: Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru> > Cc: Ekaterina Skachko <Ekaterina.Skachko@baikalelectronics.ru> > Cc: Vadim Vlasov <V.Vlasov@baikalelectronics.ru> > Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> > Cc: Paul Burton <paulburton@kernel.org> > Cc: Ralf Baechle <ralf@linux-mips.org> > Cc: Viresh Kumar <vireshk@kernel.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Vinod Koul <vkoul@kernel.org> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: dmaengine@vger.kernel.org > Cc: devicetree@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > > Serge Semin (5): > dt-bindings: dma: dw: Replace DW DMAC legacy bindings with YAML-based > one > dt-bindings: dma: dw: Add max burst transaction length property > bindings > dmaengine: dw: Add LLP and block size config accessors > dmaengine: dw: Introduce max burst length hw config > dmaengine: dw: Take HC_LLP flag into account for noLLP auto-config > > .../bindings/dma/snps,dma-spear1340.yaml | 180 ++++++++++++++++++ > .../devicetree/bindings/dma/snps-dma.txt | 69 ------- > drivers/dma/dw/core.c | 24 ++- > drivers/dma/dw/dw.c | 1 + > drivers/dma/dw/of.c | 9 + > drivers/dma/dw/regs.h | 3 + > include/linux/platform_data/dma-dw.h | 22 +++ > 7 files changed, 238 insertions(+), 70 deletions(-) > create mode 100644 Documentation/devicetree/bindings/dma/snps,dma-spear1340.yaml > delete mode 100644 Documentation/devicetree/bindings/dma/snps-dma.txt > > -- > 2.25.1 >
-- With Best Regards, Andy Shevchenko
| |