Marc Dietich wrote at Wednesday, August 10, 2011 2:25 AM: > Hi Stephen, > > > Marc Dietrich wrote at Tuesday, August 09, 2011 1:26 PM: > > > On Tuesday 09 August 2011 20:35:45 you wrote: > > > > [...] > > > > Do you need the pll_p_out4 entry? What's that driving? Check in > > > > /sys/kernel/debug/clock/clock_tree (/sys/kernel/debug is debugfs). > > > > > > I think it is only required to setup the correct (non-standard?) > > > frequency. Seems all other boards use 108 MHz which cause one of the > > > ports to fail. Don't ask me for details ... ... > > As far as I know all the clocks there are both unrelated to USB, and > > internal to the device, so the board shouldn't have any effect. In > > particular, avp.sclk/cop are for the internal media CPU/DSP, hclk/pclk > > are the internal AHB/APB bus clocks, and apbdma is for an internal DMA > > engine, currently only used for audio in the mainline kernel at least. > > Does this mean that the internal busses you mentioned are also running at low > speed? Would this be a hugh performance penality? Yes, I think this will cause a lower bus speed. I don't know how much performance impact this will have; probably mainly just peripheral register accesses, so not too much of a big deal. > > I guess I'll ask a few people internally to see if they have a clue why > > your change might be necessary. > > Also take a look at seaboard, it has the same clock setting and especially > commit dfb625f934dd40baf29ee6c43e4f130b524411a1 in the chromeos kernel: Ah yes, DAP_MCLK1/2 don't show up in the clock table. That certainly explains everything. So, I withdraw any objections to this patch. Do you want to follow it up with one that reparents sclk? I can test that on Harmony, Seaboard, and TrimSlice if you want. If not, I'll see if I can work on that a little later... > commit dfb625f934dd40baf29ee6c43e4f130b524411a1 > Author: Vincent Palatin <vpalatin@xxxxxxxxxxxx> > Date: Wed Apr 13 07:26:08 2011 -0400 > > CHROMIUM: tegra: seaboard: fix ULPI transceiver clock > > On our seaboard-based platforms, pll_p_out4 is used to clock > (through DAP_MCLK2) the external USB ULPI transceiver between the USB2 > port to mini-PCIe modem. And it needs to be set at 24Mhz for the > tranceiver to work correctly. > Revert the sclk parent to pll_c out1 (as it was before the last change) > since it needs to stay clocked at 108MHz. > > Signed-off-by: Vincent Palatin <vpalatin@xxxxxxxxxxxx> > > BUG=chrome-os-partner:3167 > TEST=Check that the Gobi modem is appearing in lsusb listing > Use the kaen DVT for browsing and suspending > > Review URL: http://codereview.chromium.org/6825076 > > Change-Id: Ia9b1bbc7860da732fb8edbbcf0bce60e82d6d8ed -- nvpublic -- 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
