On Fri, Jun 14, 2019 at 7:42 AM Peter Ujfalusi <peter.ujfalusi@xxxxxx> wrote: > > > On 14/06/2019 16.20, Rob Herring wrote: > > On Thu, Jun 13, 2019 at 2:33 PM Peter Ujfalusi <peter.ujfalusi@xxxxxx> wrote: > >> > >> Rob, > >> > >> On 13/06/2019 21.16, Rob Herring wrote: > >>>> +Remote PSI-L endpoint > >>>> + > >>>> +Required properties: > >>>> +-------------------- > >>>> +- ti,psil-base: PSI-L thread ID base of the endpoint > >>>> + > >>>> +Within the PSI-L endpoint node thread configuration subnodes must present with: > >>>> +ti,psil-configX naming convention, where X is the thread ID offset. > >>> > >>> Don't use vendor prefixes on node names. > >> > >> OK. > >> > >>>> + > >>>> +Configuration node Required properties: > >>>> +-------------------- > >>>> +- linux,udma-mode: Channel mode, can be: > >>>> + - UDMA_PKT_MODE: for Packet mode channels (peripherals) > >>>> + - UDMA_TR_MODE: for Third-Party mode > >>> > >>> This is hardly a common linux thing. What determines the value here. > >> > >> Unfortunately it is. > > > > No, it's a feature of your h/w and in no way is something linux > > defined which is the point of 'linux' prefix. > > The channel can be either Packet or TR mode. The HW is really flexible > on this (and on other things as well). > It just happens that Linux need to use specific channels in a specific mode. > > Would it help if we assume that all channels are used in Packet mode, > but we have linux,tr-mode bool to indicate that the given channel in > Linux need to be used in TR mode. Your use of 'linux' prefix is wrong. Stop using it. > >> Each channel can be configured to Packet or TR mode. For some > >> peripherals it is true that they only support packet mode, these are the > >> newer PSI-L native peripherals. > >> For these channels a udma-mode property would be correct. > >> > >> But we have legacy peripherals as well and they are serviced by PDMA > >> (which is a native peripheral designed to talk to the given legacy IP). > >> We can use either packet or TR mode in UDMAP to talk to PDMAs, it is in > >> most cases clear what to use, but for example for audio (McASP) channels > >> Linux is using TR channel because we need cyclic DMA while for example > >> RTOS is using Packet mode as it fits their needs better. > >> > >> Here I need to prefix the udma-mode with linux as the mode is used by > >> Linux, but other OS might opt to use different channel mode. > > > > So you'd need <os>,udma-mode? That doesn't work... If the setting is > > per OS, then it belongs in the OS because the same dtb should work > > across OS's. > > So I should have a table for the thread IDs in the DMA driver and mark > channels as TR or Packet in there for Linux use? Perhaps. I haven't heard any reasons why you need this in DT. If Linux is dictating the modes, then sounds like it should be in Linux. But really, I don't fully understand what you are doing here to tell you what to do beyond using 'linux' prefix is wrong. > Or just an array which would mark the non packet PSI-L thread IDs? > > I still prefer to have this coming via DT as a Linux parameter as other > OS is free to ignore the linux,udma-mode, but as I said there are > certain channels which must be used in Linux in certain mode while > others in different mode. A DT client is free to ignore any DT property. You don't need a client prefix for that. > >> The reason why this needs to be in the DT is that when the channel is > >> requested we need to configure the mode and it can not be swapped > >> runtime easily between Packet and TR mode. > > > > So when the client makes the channel request, why doesn't it specify the mode? > > This is UDMAP internal information on what type of Descriptors the > channel will expect and how it is going to dispatch the work. > > Packet and TR mode at the end does the same thing, but in a completely > different way. > > - Péter > > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. > Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
