Hi, > Martin Sperl <martin@xxxxxxxxx> hat am 11. Februar 2016 um 14:15 geschrieben: > > The only real difference is this diff: > @@ -41,6 +41,4 @@ > 20101000.cprman: bcm2835_clock_get_parent - pwm > 20101000.cprman: bcm2835_clock_get_parent - hsm > 20101000.cprman: bcm2835_pll_on - pllc > - 20101000.cprman: bcm2835_pll_on - plld > - 20101000.cprman: bcm2835_clock_on - uart > 20101000.cprman: bcm2835_clock_on - emmc > > so plld and uart are not started for the console=ttyS0 case. > > After I instrumented clk-bcm2835.c to see what happens in the driver > and running: /sbin/getty -a root -L ttyAMA0 115200 vt100 > > I get the following: > [ 146.342341] bcm2835-clk 20101000.cprman: bcm2835_pll_on - plld > [ 146.348426] bcm2835-clk 20101000.cprman: bcm2835_clock_on - uart > [ 146.354639] uart-pl011 20201000.uart: no DMA platform data > [ 146.375535] bcm2835-clk 20101000.cprman: bcm2835_clock_off - uart > [ 146.381776] bcm2835-clk 20101000.cprman: bcm2835_clock_wait_busy - uart > [ 146.388595] bcm2835-clk 20101000.cprman: bcm2835_pll_off - plld > [ 146.396574] bcm2835-clk 20101000.cprman: bcm2835_pll_on - plld > [ 146.502551] bcm2835-clk 20101000.cprman: plld: couldn't lock PLL > [ 146.508726] ------------[ cut here ]------------ > [ 146.513448] WARNING: CPU: 0 PID: 2349 at drivers/clk/clk.c:680 > clk_core_disa) > [ 146.522673] ---[ end trace 33268753126338e9 ]--- > [ 146.527478] ------------[ cut here ]------------ > [ 146.532224] WARNING: CPU: 0 PID: 2349 at drivers/clk/clk.c:575 > clk_core_unpr) > [ 146.541866] ---[ end trace 33268753126338ea ]--- > > So I wonder why we would disable and reenable the plld and uart clock I think the reason for this behavior can be found in the uart-pl011 driver which plays with the clocks. According to the clock tree "plld" seems to be critical and shouldn't be disabled? > > Note that just adding a return in bcm2835_pll_off like this: > @@ -900,6 +905,9 @@ static void bcm2835_pll_off(struct clk_hw *hw) > struct bcm2835_cprman *cprman = pll->cprman; > const struct bcm2835_pll_data *data = pll->data; > > + dev_err(cprman->dev, "%s - %s\n", __FUNCTION__, clk_hw_get_name(hw)); > + return; > + > cprman_write(cprman, data->cm_ctrl_reg, CM_PLL_ANARST); > cprman_write(cprman, data->a2w_ctrl_reg, A2W_PLL_CTRL_PWRDN); > } > > avoids the crash, but the tty is non-functional. > > Calling sequence of the clock driver is: > [ 145.022546] bcm2835-clk 20101000.cprman: bcm2835_pll_on - plld > [ 145.028619] bcm2835-clk 20101000.cprman: bcm2835_clock_on - uart > [ 145.034807] uart-pl011 20201000.uart: no DMA platform data > [ 145.045089] bcm2835-clk 20101000.cprman: bcm2835_clock_off - uart > [ 145.051418] bcm2835-clk 20101000.cprman: bcm2835_clock_wait_busy - uart > [ 145.058215] bcm2835-clk 20101000.cprman: bcm2835_pll_off - plld > [ 145.065779] bcm2835-clk 20101000.cprman: bcm2835_pll_on - plld > [ 145.071761] bcm2835-clk 20101000.cprman: bcm2835_clock_on - uart > > debugfs shows the following after the above: > root@raspcm:~# head /sys/kernel/debug/clk/uart*/clk_rate > ==> /sys/kernel/debug/clk/uart0_pclk/clk_rate <== > 3000000 > > ==> /sys/kernel/debug/clk/uart1_pclk/clk_rate <== > 125000000 > > ==> /sys/kernel/debug/clk/uart/clk_rate <== > 2997598 > > Is this maybe related to the uart0_pclk, uart1_pclk, apb_pclk > clocks created and registered in bcm2835_init_clocks? Related or not i think we should get the rid off them. > > Any Ideas? > > Thanks, > Martin > > _______________________________________________ > linux-rpi-kernel mailing list > linux-rpi-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-rpi-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
