Hi Peter, Am Mittwoch, den 10.12.2014, 13:09 +0800 schrieb Peter Chen: > On Tue, Dec 09, 2014 at 05:13:35PM +0100, Philipp Zabel wrote: > > On i.MX6Q, the USBMISC registers are clocked by the IPG clock, > > so there is no need to enable USBOH3 for the USBMISC driver. > > Access the registers at usbmisc needs the same clock with chipidea core, > both are usboh3. Alright, I'll drop this patch. It was my understanding that the usbmisc register space is clocked by ipg_clk_s, which is not gated by usboh3_clk_enable: Having a look at the "i.MX 6Dual/6Quad Applications Processor Reference Manual, Rev. 1, 04/2013", Figure 65-1 "USB block diagram" shows the USB Control Register (usbmisc) directly connected via "IP Bus1" separately from the host cores (these are connected behind a PL301). In chapter 18.4 "System Clocks", the table entry for the block instance "USB" shows that the usboh3_clk_enable bit gates only the ipg_ahb_clk, ipg_clk_s_pl301, test_clk_240m, test_clk_480m, and test_clk_60m inputs to the USB block. The ipg_clk_s (from ipg_clk_root) and ipg_clk_32khz inputs are not marked as gated. Still, it seems that indeed the usbmisc region is inaccessible after gating usboh3 by unbinding the usb drivers. regards Philipp -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
