On Fri, Mar 02, 2018 at 09:02:07AM +0000, Jon Hunter wrote: > > On 01/03/18 07:41, Peter De Schrijver wrote: > > On Wed, Feb 28, 2018 at 08:20:47PM +0300, Dmitry Osipenko wrote: > >> On 28.02.2018 17:14, Peter De Schrijver wrote: > >>> On Wed, Feb 28, 2018 at 03:00:23PM +0300, Dmitry Osipenko wrote: > >>>> On 28.02.2018 12:36, Peter De Schrijver wrote: > >>>>> On Tue, Feb 27, 2018 at 02:59:11PM +0300, Dmitry Osipenko wrote: > >>>>>> On 27.02.2018 02:04, Marcel Ziswiler wrote: > >>>>>>> On Mon, 2018-02-26 at 15:42 +0300, Dmitry Osipenko wrote: > >>>>>>>> On 23.02.2018 02:04, Marcel Ziswiler wrote: > >>>>>>>>> Turns out latest upstream U-Boot does not configure/enable pllu > >>>>>>>>> which > >>>>>>>>> leaves it at some default rate of 500 kHz: > >>>>>>>>> > >>>>>>>>> root@apalis-t30:~# cat /sys/kernel/debug/clk/clk_summary | grep > >>>>>>>>> pll_u > >>>>>>>>> pll_u 3 3 0 500000 > >>>>>>>>> 0 > >>>>>>>>> > >>>>>>>>> Of course this won't quite work leading to the following messages: > >>>>>>>>> > >>>>>>>>> [ 6.559593] usb 2-1: new full-speed USB device number 2 using > >>>>>>>>> tegra- > >>>>>>>>> ehci > >>>>>>>>> [ 11.759173] usb 2-1: device descriptor read/64, error -110 > >>>>>>>>> [ 27.119453] usb 2-1: device descriptor read/64, error -110 > >>>>>>>>> [ 27.389217] usb 2-1: new full-speed USB device number 3 using > >>>>>>>>> tegra- > >>>>>>>>> ehci > >>>>>>>>> [ 32.559454] usb 2-1: device descriptor read/64, error -110 > >>>>>>>>> [ 47.929777] usb 2-1: device descriptor read/64, error -110 > >>>>>>>>> [ 48.049658] usb usb2-port1: attempt power cycle > >>>>>>>>> [ 48.759475] usb 2-1: new full-speed USB device number 4 using > >>>>>>>>> tegra- > >>>>>>>>> ehci > >>>>>>>>> [ 59.349457] usb 2-1: device not accepting address 4, error -110 > >>>>>>>>> [ 59.509449] usb 2-1: new full-speed USB device number 5 using > >>>>>>>>> tegra- > >>>>>>>>> ehci > >>>>>>>>> [ 70.069457] usb 2-1: device not accepting address 5, error -110 > >>>>>>>>> [ 70.079721] usb usb2-port1: unable to enumerate USB device > >>>>>>>>> > >>>>>>>>> Fix this by actually allowing the rate also being set from within > >>>>>>>>> the Linux kernel. > >>>>> > >>>>> I think the best solution to this problem would be to make pll_u a fixed > >>>>> clock and enable it and program the rate if it's not enabled at boot. > >>>> > >>>> Oh, right. PLL_U rate is actually configurable, somehow I missed it in TRM > >>>> yesterday.. So set/round_rate() for PLL_U are actually needed and the patch is > >>>> correct. Seems only T20 misses PLL_U in the init table, probably worth to add it > >>>> there. > >>>> > >>> > >>> AFAIK we only use one rate ever? > >> > >> IIUC, PLL_U has 3 outputs and output dividers are fixed in HW. So yes, we are > >> setting PLL_U to one rate - 480MHz to get out1-480MHz, out2-60MHz and out3-12MHz. > >> > > > > Indeed. And given that it's hw controlled anyway, I don't see why we can't make > > it a fixed clock and handle the init at kernel boot depending on what the > > bootloader has done. > > Peter, are you suggesting we implement the equivalent to > tegra210_init_pllu()? This does look a bit more involved that what this > change is doing. Is there a simple way to do what you are suggesting? > Basically yes. Peter. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
