Russell, On 07/12/2018 15.57, Russell King - ARM Linux wrote: > On Fri, Dec 07, 2018 at 03:40:13PM +0200, Peter Ujfalusi wrote: >> Russell, >> >> On 07/12/2018 14.52, Russell King - ARM Linux wrote: >>> It was noticed that unbinding and rebinding the KSZ8851 ethernet >>> resulted in the driver reporting "failed to read device ID" at probe. >>> Probing the reset line with a 'scope while repeatedly attempting to >>> bind the driver in a shell loop revealed that the KSZ8851 RSTN pin is >>> constantly held at zero, meaning the device is held in reset, and >>> does not respond on the SPI bus. >>> >>> Experimentation with the startup delay on the regulator set to 50ms >>> shows that the reset is positively released after 20ms. >>> >>> Schematics for this board are not available, and the traces are buried >>> in the inner layers of the board which makes tracing where the RSTN pin >>> extremely difficult. We can only guess that the RSTN pin is wired to a >>> reset generator chip driven off the ethernet supply, which fits the >>> observed behaviour. >> >> Based on the schematics of the Blaze device (which should be very close >> to SDP4430): >> >> TPS22902YFPR is used as the regulator switch (gpio48 controlled) >> The VOUT is routed to TPS3808G01DBV (SCH Note: Threshold set at 90%. >> Vsense: 0.405V). >> >> According to the TPS3808 data sheet the RESET delay time when Ct is open >> (this is the case in the schema): MIN/TYP/MAX: 12/20/28 ms. >> >> The 20ms you are seeing confirms this setup. > > Thanks for the confirmation and information. The Blaze schematics > are also unavailable afaics. Even with the delay I can not get the ethernet working on Blaze. It supposed to be mostly the same HW as sdp (we load the same omap4-sdp.dtb). [ 2.576599] ks8851 spi0.0: spi0.0 supply vdd-io not found, using dummy regulator [ 2.584045] ks8851 spi0.0: Linked as a consumer to regulator.0 [ 2.584136] ks8851 spi0.0: Linked as a consumer to regulator.4 [ 2.595916] ks8851 spi0.0: message enable is 0 [ 2.602661] ks8851 spi0.0: failed to read device ID [ 2.607604] ks8851 spi0.0: Dropping the link to regulator.4 [ 2.607604] ks8851 spi0.0: Dropping the link to regulator.0 I can not recall when was the last time it worked, could be years ago. - Péter Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
