On Tue, 2022-01-18 at 21:10 +0000, Thinh Nguyen wrote: > Hi Sean, > > Sean Anderson wrote: > > Hi Thinh, > > > > On 1/18/22 3:00 PM, Thinh Nguyen wrote: > > > Sean Anderson wrote: > > > > Hi Thinh, > > > > > > > > On 1/18/22 2:46 PM, Thinh Nguyen wrote: > > > > > Hi Sean, > > > > > > > > > > Baruch Siach wrote: > > > > > > Hi Sean, Thinh, > > > > > > > > > > > > On Fri, Jan 14 2022, Sean Anderson wrote: > > > > > > > This is a rework of patches 3-5 of [1]. It attempts to correctly > > > > > > > program > > > > > > > REFCLKPER and REFCLK_FLADJ based on the reference clock > > > > > > > frequency. > > > > > > > Since > > > > > > > we no longer need a special property duplicating this > > > > > > > configuration, > > > > > > > snps,ref-clock-period-ns is deprecated. > > > > > > > > > > > > > > Please test this! Patches 3/4 in this series have the effect of > > > > > > > programming REFCLKPER and REFCLK_FLADJ on boards which already > > > > > > > configure > > > > > > > the "ref" clock. I have build tested, but not much else. > > > > > > > > > > > > > > [1] > > > > > > > https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/20220114044230.2677283-1-robert.hancock@xxxxxxxxxx/__;!!A4F2R9G_pg!M3zKxDZC9a_etqzXo7GSEMTHRWfc1wR_84wwM4-fShiA35CsGcxcTEffHPbprbdC4d2R$ > > > > > > > > > > > > > > > > > > > > > > > > > > Thinh, you suggested the dedicated DT property for the reference > > > > > > clock: > > > > > > > > > > > > > > > > > > https://urldefense.com/v3/__https://lore.kernel.org/all/d5acb192-80b9-36f7-43f5-81f21c4e6ba0@xxxxxxxxxxxx/__;!!A4F2R9G_pg!M3zKxDZC9a_etqzXo7GSEMTHRWfc1wR_84wwM4-fShiA35CsGcxcTEffHPbprbpOFmvX$ > > > > > > > > > > > > > > > > > > > > > > > > Can you comment on this series? > > > > > > > > > > > > > > > > Unless there's a good way to pass this information for PCI devices, > > > > > my > > > > > opinion hasn't changed. (Btw, I don't think creating a dummy clock > > > > > provider and its dummy ops is a good solution as seems to complicate > > > > > and > > > > > bloat the PCI glue drivers). > > > > > > > > Can you explain your situation a bit more? I'm not sure how you can > > > > access a device tree property but not add a fixed-rate clock. > > > > > > > > --Sean > > > > > > Currently for dwc3 pci devices, we have glue drivers that create a > > > platform_device with specific properties to pass to the dwc3 core > > > driver. Without a ref clock property, we would need another way to pass > > > this information to the core driver or another way for the dwc3 core > > > driver to check for specific pci device's properties and quirks. > > > > The primary problem with the existing binding is that it does not > > contain enough information to calculate the fractional period. With the > > frequency, we can calculate the correct values for the registers without > > needing an additional binding. So we need to transition to some kind of > > frequency-based system. So perhaps we should add a "ref-clock-frequency" > > property and use that as a default for when the clock is missing. > > > > Not sure about others, but that's fine with me. The other solution is to > rework the dwc3 drivers as Robert noted, but that requires some work. > Seems reasonable enough for a short-term fix anyway. > Thanks, > Thinh > -- Robert Hancock Senior Hardware Designer, Calian Advanced Technologies www.calian.com
