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. > 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. > 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? Rob
