On Tue, Jan 20, 2015 at 02:52:21PM +0000, Graeme Gregory wrote: > On Tue, Jan 20, 2015 at 02:33:00PM +0000, Andre Przywara wrote: > > > > > > On 20/01/15 14:26, Graeme Gregory wrote: > > > On Tue, Jan 20, 2015 at 01:55:01PM +0000, Andre Przywara wrote: > > >> Hi Graeme, > > >> > > >> On 20/01/15 13:08, Graeme Gregory wrote: > > >>> On Fri, Jan 16, 2015 at 05:22:56PM +0000, Andre Przywara wrote: > > >>>> The ARM Server Base System Architecture[1] document describes a > > >>>> generic UART which is a subset of the PL011 UART. > > >>>> It lacks DMA support, baud rate control and modem status line > > >>>> control, among other things. > > >>>> The idea is to move the UART initialization and setup into the > > >>>> firmware (which does this job today already) and let the kernel just > > >>>> use the UART for sending and receiving characters. > > >>>> > > >>>> This patchset integrates support for this UART subset into the > > >>>> existing PL011 driver - basically by refactoring some > > >>>> functions and providing a new uart_ops structure for it. It also has > > >>>> a separate probe function to be not dependent on AMBA/PrimeCell. > > >>>> It provides a device tree binding, but can easily be adapted to other > > >>>> device configuration systems. > > >>>> Beside the obvious effect of code sharing reusing most of the PL011 > > >>>> code has the advantage of not introducing another serial device > > >>>> prefix, so it can go with ttyAMA, which seems to be pretty common. > > >>>> > > >>>> This series relies on Dave's recent PL011 fix[2], which gets rid of > > >>>> the loopback trick to get the UART going. There is a repo at [3] > > >>>> (branch sbsa-uart/v1), which has this patch already integrated. > > >>>> > > >>>> Patch 1/10 contains a bug fix which applies to the PL011 part also, > > >>>> it should be considered regardless of the rest of the series. > > >>>> Patch 2-7 refactor some PL011 functions by splitting them up into > > >>>> smaller pieces, so that most of the code can be reused later by the > > >>>> SBSA part. > > >>>> Patch 8 and 9 introduce two new properties for the vendor structure, > > >>>> this is for SBSA functionality which cannot be controlled by > > >>>> separate uart_ops members only. > > >>>> Patch 10 then finally drops in the SBSA specific code, by providing > > >>>> a new uart_ops, vendor struct and probe function for it. Also the new > > >>>> device tree binding is documented. > > >>>> > > >>>> For testing you should be able to take any hardware which has a PL011 > > >>>> and change the DT to use a "arm,sbsa-uart" compatible string. > > >>>> Of course testing with a real SBSA Generic UART is welcomed! > > >>>> > > >>> I have tested this series on Juno where it seems to work and also on FVP > > >>> model where there are some issues. > > >>> > > >>> On the FVP when we enter usespace a couple of 32 character strings are > > >>> printed then nothing else. 32 Characters is a suspicious number. > > >> > > >> Can you try to add: > > >> -C bp.pl011_uart0.untimed_fifos=0 > > >> to your model command line? (given that your model supports this option) > > >> > > >> We discovered that lately, also not sure how the default for this > > >> setting is handled these days in the various model versions. > > >> > > >> We are about to investigate this here atm. > > >> This issue seems to be introduced by Dave's FIFO patch. > > >> > > > > > > With this setting userspace functions better but loses characters > > > fairly regularly. > > > > Are you using arm,sbsa-uart in the DT, but a default PL011 in the model > > config? In my model the default PL011 version has a 16 byte FIFO only, > > specifying: > > -C bp.pl011_uart0.revision="r1p5" > > upgrades this to the SBSA specified 32 byte FIFO size. > > With this setting I don't see any character loses. > > > Yes with this setting all works with untimed_fifos=0 > > I was not aware of the differences in versions thanks. > Now I know how to correctly configure model I have now tested on FVP and Juno so feel free to add my Tested-by: Graeme -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html