serial: clk: bcm2835: Strange effects when using aux-uart in console
From: Martin Sperl <hidden>
Date: 2016-02-13 11:53:20
Also in:
linux-clk, linux-serial
quoted hunk ↗ jump to hunk
On 13.02.2016, at 11:01, Stefan Wahren [off-list ref] wrote:diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c index 637f8ae..03d95c1 100644 --- a/drivers/clk/bcm/clk-bcm2835.c +++ b/drivers/clk/bcm/clk-bcm2835.c@@ -1638,6 +1675,9 @@ static int bcm2835_clock_set_rate(struct clk_hw *hw,enum bcm2835_clock_mash_type mash = divmash_get_mash(dm); u32 ctl; + if (cprman_read(cprman, data->ctl_reg) & CM_BUSY) + pr_warn("%s: clk still busy from %d\n", __func__, cprman->func_code); + spin_lock(&cprman->regs_lock); /* if div and mash are identical, then there is nothing to do */@@ -1663,6 +1703,11 @@ static int bcm2835_clock_set_rate(struct clk_hw *hw,unlock_exit: spin_unlock(&cprman->regs_lock); + cprman->func_code = 10; + + if (cprman_read(cprman, data->ctl_reg) & CM_BUSY) + pr_warn("%s: clk now busy from %d\n", __func__, cprman->func_code); + return 0; }
Seems as if you apply it on top of (parts of) my patchset - not on top of a clean 4.5-rc3. Anyway - after some fixing I get the following outputs - the amba-pl011 driver is still patched with debug messages: After boot with aux-uart as tty: root at raspcm:~# dmesg | grep bcm2835 [ 0.018172] bcm2835: system timer (irq = 27) [ 0.711388] bcm2835-aux-uart 20215040.serial: could not get clk: -517 [ 1.649124] bcm2835-rng 20104000.rng: hwrng registered [ 2.051190] bcm2835_clock_on: clk still busy from 6 [ 2.056159] bcm2835_clock_on: clk now busy from 9 [ 8.062743] bcm2835-wdt 20100000.watchdog: Broadcom BCM2835 watchdog timer [ 12.042105] bcm2835-i2s 20203000.i2s: can't request region for resource [mem 0x20101098-0x20101099] [ 12.191701] bcm2835-i2s: probe of 20203000.i2s failed with error -16 Loading the module: root at raspcm:~# modprobe amba-pl011 [ 106.685812] Serial: AMBA PL011 UART driver [ 106.693702] uart-pl011 20201000.uart: pl011_setup_port: f0201000 20201000 [ 106.702109] 20201000.uart: ttyAMA0 at MMIO 0x20201000 (irq = 81, base_baud = 0) is a PL011 rev2 root at raspcm:~# and starting getty: root at raspcm:~# /sbin/getty -a root -L ttyAMA0 115200 vt100 [ 137.851123] pl011_startup - start [ 137.854538] pl011_hwinit - prepare-enable [ 137.858772] bcm2835_clock_on: clk still busy from 6 [ 137.863755] bcm2835_clock_on: clk now busy from 9 [ 137.868590] pl011_hwinit - prepare-enable - ret = 0 [ 137.875249] uart-pl011 20201000.uart: no DMA platform data [ 137.880940] pl011_startup - exit [ 137.888840] pl011_shutdown - start [ 137.892360] pl011_shutdown - disable_unprepare [ 137.896933] bcm2835_clock_off: clk still busy from 9 [ 137.902112] pl011_shutdown - exit [ 137.907233] pl011_startup - start [ 137.910713] pl011_hwinit - prepare-enable [ 137.914808] bcm2835_pll_on: PLL still locked from 1 [ 138.019876] bcm2835-clk 20101000.cprman: plld: couldn't lock PLL [ 138.026000] pl011_hwinit - prepare-enable - ret = -110 [ 138.031266] pl011_startup - error = -110 - disable_unprepare [ 138.037048] ------------[ cut here ]------------ [ 138.041777] WARNING: CPU: 0 PID: 2377 at drivers/clk/clk.c:680 clk_core_disable+0x34/0xf0() [ 138.051063] ---[ end trace dd2f225b2af4c32c ]--- [ 138.055859] ------------[ cut here ]------------ [ 138.060627] WARNING: CPU: 0 PID: 2377 at drivers/clk/clk.c:575 clk_core_unprepare+0x34/0x110() [ 138.070321] ---[ end trace dd2f225b2af4c32d ]--- No HDMI output - this time no ?flashing? - just no signal. Machine is crashed - the attached AXIS USB network card (0b95:772b) just transmits identical packets on the network without stopping? I have also disabled the DMA-engine in the amba-pl011 driver (in the driver itself add: #undef CONFIG_DMA_ENGINE) and then I get: root at raspcm:/build/linux# /sbin/getty -a root -L ttyAMA0 115200 vt100 [ 97.010287] pl011_startup - start [ 97.013698] pl011_hwinit - prepare-enable [ 97.017931] bcm2835_clock_on: clk still busy from 6 [ 97.022905] bcm2835_clock_on: clk now busy from 9 [ 97.027755] pl011_hwinit - prepare-enable - ret = 0 [ 97.034378] pl011_startup - exit [ 97.041197] pl011_shutdown - start [ 97.044728] pl011_shutdown - disable_unprepare [ 97.049386] bcm2835_clock_off: clk still busy from 9 [ 97.054458] pl011_shutdown - exit [ 97.059633] pl011_startup - start [ 97.063033] pl011_hwinit - prepare-enable [ 97.067533] bcm2835_pll_on: PLL still locked from 1 [ 97.172655] bcm2835-clk 20101000.cprman: plld: couldn't lock PLL [ 97.178838] pl011_hwinit - prepare-enable - ret = -110 [ 97.184075] pl011_startup - error = -110 - disable_unprepare [ 97.189905] ------------[ cut here ]------------ [ 97.194640] WARNING: CPU: 0 PID: 2442 at drivers/clk/clk.c:680 clk_core_disab le+0x34/0xf0() [ 97.203924] ---[ end trace 3e878f70606eba69 ]--- [ 97.208692] ------------[ cut here ]------------ [ 97.213429] WARNING: CPU: 0 PID: 2442 at drivers/clk/clk.c:575 clk_core_unpre pare+0x34/0x110() [ 97.223096] ---[ end trace 3e878f70606eba6a ]? Not sure why the pl011 driver runs the startup/shutdown/startup loop. Martin