Messages in this thread | | | Date | Wed, 05 Oct 2011 22:47:23 +0200 | From | Wojciech Zabołotny <> | Subject | BUG in kernel 3.0.4 for mach-at91 - atmel_tcb.1 is not detected in tc_probe, fix provided |
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Hi,
I've ported my driver, which uses the atmel_tcb.1 block as PWM source (in AT91SAM9260). The code worked perfectly in kernel.2.6.29.3, but now during the initialization I get the following error:
atmel_tcb: probe of atmel_tcb.1 failed with error -22
I have added printk invocations in the tc_probe routine, and I've found, that the problem occures, when tc_probe attempts to get clock for atmel_tcb.1 (In this line: http://lxr.linux.no/linux+v3.0.4/driver ... lib.c#L125 <http://lxr.linux.no/linux+v3.0.4/drivers/misc/atmel_tclib.c#L125> )
The atmel_tcb.0 is correctly used as clocksource: tcb_clksrc: tc0 at 12.916 MHz
I have found, that the tc_probe always looks for "t0_clk", "t1_clk" and "t2_clk", and function at91_add_device_tc performs the following operations:
( http://lxr.linux.no/linux+*/arch/arm/ma ... ces.c#L599 <http://lxr.linux.no/linux+*/arch/arm/mach-at91/at91sam9260_devices.c#L599> ) static void __init at91_add_device_tc(void) { /* this chip has a separate clock and irq for each TC channel */ at91_clock_associate("tc0_clk", &at91sam9260_tcb0_device.dev, "t0_clk"); at91_clock_associate("tc1_clk", &at91sam9260_tcb0_device.dev, "t1_clk"); at91_clock_associate("tc2_clk", &at91sam9260_tcb0_device.dev, "t2_clk"); platform_device_register(&at91sam9260_tcb0_device); at91_clock_associate("tc3_clk", &at91sam9260_tcb1_device.dev, "t0_clk"); at91_clock_associate("tc4_clk", &at91sam9260_tcb1_device.dev, "t1_clk"); at91_clock_associate("tc5_clk", &at91sam9260_tcb1_device.dev, "t2_clk"); platform_device_register(&at91sam9260_tcb1_device); }
While the code mapping the clock names in 3.0.4 has the following form:
(see: http://lxr.linux.no/linux+*/arch/arm/ma ... 260.c#L234 <http://lxr.linux.no/linux+*/arch/arm/mach-at91/at91sam9260.c#L234> ) static struct clk_lookup periph_clocks_lookups[] = { CLKDEV_CON_DEV_ID("spi_clk", "atmel_spi.0", &spi0_clk), CLKDEV_CON_DEV_ID("spi_clk", "atmel_spi.1", &spi1_clk), CLKDEV_CON_DEV_ID("t0_clk", "atmel_tcb.0", &tc0_clk), CLKDEV_CON_DEV_ID("t1_clk", "atmel_tcb.0", &tc1_clk), CLKDEV_CON_DEV_ID("t2_clk", "atmel_tcb.0", &tc2_clk), CLKDEV_CON_DEV_ID("t3_clk", "atmel_tcb.1", &tc3_clk), CLKDEV_CON_DEV_ID("t4_clk", "atmel_tcb.1", &tc4_clk), CLKDEV_CON_DEV_ID("t5_clk", "atmel_tcb.1", &tc5_clk), CLKDEV_CON_DEV_ID("pclk", "ssc.0", &ssc_clk), };
To assure correct detection and operation of atmel_tcb.1, I had to change the above code as shown below:
static struct clk_lookup periph_clocks_lookups[] = { CLKDEV_CON_DEV_ID("spi_clk", "atmel_spi.0", &spi0_clk), CLKDEV_CON_DEV_ID("spi_clk", "atmel_spi.1", &spi1_clk), CLKDEV_CON_DEV_ID("t0_clk", "atmel_tcb.0", &tc0_clk), CLKDEV_CON_DEV_ID("t1_clk", "atmel_tcb.0", &tc1_clk), CLKDEV_CON_DEV_ID("t2_clk", "atmel_tcb.0", &tc2_clk), CLKDEV_CON_DEV_ID("t0_clk", "atmel_tcb.1", &tc3_clk), CLKDEV_CON_DEV_ID("t1_clk", "atmel_tcb.1", &tc4_clk), CLKDEV_CON_DEV_ID("t2_clk", "atmel_tcb.1", &tc5_clk), CLKDEV_CON_DEV_ID("pclk", "ssc.0", &ssc_clk), };
-- Regards, Wojciech M. Zabolotny
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