Hi, > -----Original Message----- > From: Marek Vasut <ma...@denx.de> > Sent: Tuesday, November 19, 2024 7:49 PM > To: Abbarapu, Venkatesh <venkatesh.abbar...@amd.com>; u-boot@lists.denx.de > Cc: Simek, Michal <michal.si...@amd.com>; fabrice.gasn...@foss.st.com; git > (AMD-Xilinx) <g...@amd.com> > Subject: Re: [PATCH v11 3/7] usb: onboard-hub: add support for Microchip > USB5744 > > On 11/19/24 4:22 AM, Abbarapu, Venkatesh wrote: > > [...] > > >>>>>> Is there a matching delay requirement specified in the USB hub > >>>>>> datasheet or is this a workaround for some board-specific behavior ? > >>>>> The matching delay is not specified in the USB5744 hub document, > >>>>> but based on > >>>> testing on 2 boards with the above-mentioned delay i2c failures > >>>> were not > >> observed. > >>>> Is this 10ms a board-specific reset delay ? > >>>> Why is it in a generic driver ? > >>> On our boards we observed i2c failures when we set the reset delay > >>> as 5us and power on delay as 1ms as per the USB5744 datasheet. The > >>> reason of adding 10ms delay is because of i2c failures and the linux > >>> reference is > >>> https://github.com/torvalds/linux/commit/908f61bedb2c40c6d856bbfd7f8 > >>> 70 > >>> b967a4cb498 Do you have anything with respect to these delays, as > >>> you might have tested on some other boards? If anything, please let me > >>> know. > >> If the 10ms delay is a board specific delay, then this has to be > >> handled in a board specific way, not hard-coded in the driver. > >> Probably add some new property which specifies the extra board > >> specific reset delay, but be sure to run that property by the Linux kernel > maintainers too. > > Thanks. I will check how to add the board specific delay as new property. > > Add some reset-...-us , similar to what ethernet PHYs already do in DT. Sure...will check and initiate discussion with the Linux team.
> > > As this delay might be specific to the boards which we tested. > > There won't be any issue if we can add the default "reset_delay"(5us) and > "power_on_delay" (1ms) from the USB5744 datasheet, as other boards will be > working without any board specific delay? > Right, the driver has to be generic , that means it should contain delays > specified in > the datasheet. Board specific delays have to be configured in board specific > DTs. Thanks. I have updated the delays based on usb5744 specification in the [PATCH v13 3/7] usb: onboard-hub: add support for Microchip USB5744 Please review. Thanks Venkatesh
