Re: [alsa-devel] [RFC PATCH 16/40] soundwire: cadence_master: improve startup sequence with link hw_reset

2019-07-26 Thread Pierre-Louis Bossart
+static int do_reset(struct sdw_cdns *cdns) +{ + int ret; + + /* program maximum length reset to be safe */ + cdns_updatel(cdns, CDNS_MCP_CONTROL, +CDNS_MCP_CONTROL_RST_DELAY, +CDNS_MCP_CONTROL_RST_DELAY); + + /* use hardware gener

Re: [alsa-devel] [RFC PATCH 16/40] soundwire: cadence_master: improve startup sequence with link hw_reset

2019-07-26 Thread Guennadi Liakhovetski
On Thu, Jul 25, 2019 at 06:40:08PM -0500, Pierre-Louis Bossart wrote: > Enable interrupts first, then engage hardware bus reset with maximum > duration to make sure the Slave(s) correctly detect the reset pattern > and to ensure electrical conflicts can be resolved. > > Without these changes the i

[RFC PATCH 16/40] soundwire: cadence_master: improve startup sequence with link hw_reset

2019-07-25 Thread Pierre-Louis Bossart
Enable interrupts first, then engage hardware bus reset with maximum duration to make sure the Slave(s) correctly detect the reset pattern and to ensure electrical conflicts can be resolved. Without these changes the initialization is randomly corrupted by bus clashes, parity errors and Slave atta