| Message ID | 20220404085822.84135-1-iivanov@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | clk: bcm2835: Round UART input clock up | expand |
Hi "Ivan,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on clk/clk-next]
[also build test WARNING on v5.18-rc1 next-20220404]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/intel-lab-lkp/linux/commits/Ivan-T-Ivanov/clk-bcm2835-Round-UART-input-clock-up/20220404-170105
base: https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git clk-next
config: riscv-randconfig-r042-20220404 (https://download.01.org/0day-ci/archive/20220404/202204041850.zEjvoN6Y-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/79c34b5361c9ab155da3175cfc964b67b9a06eab
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Ivan-T-Ivanov/clk-bcm2835-Round-UART-input-clock-up/20220404-170105
git checkout 79c34b5361c9ab155da3175cfc964b67b9a06eab
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=riscv SHELL=/bin/bash drivers/clk/bcm/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> drivers/clk/bcm/clk-bcm2835.c:997:15: warning: no previous prototype for 'bcm2835_clock_round' [-Wmissing-prototypes]
997 | unsigned long bcm2835_clock_round(unsigned long clk)
| ^~~~~~~~~~~~~~~~~~~
vim +/bcm2835_clock_round +997 drivers/clk/bcm/clk-bcm2835.c
996
> 997 unsigned long bcm2835_clock_round(unsigned long clk)
998 {
999 unsigned long scaler;
1000
1001 /*
1002 * If increasing a clock by less than 0.1% changes it
1003 * from ..999.. to ..000.., round up.
1004 */
1005 scaler = 1;
1006 while (scaler * 100000 < clk)
1007 scaler *= 10;
1008 if ((clk + scaler - 1) / scaler % 1000 == 0)
1009 clk = (clk / scaler + 1) * scaler;
1010
1011 return clk;
1012 }
1013
diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c index 3ad20e75fd23..f293cde427b7 100644 --- a/drivers/clk/bcm/clk-bcm2835.c +++ b/drivers/clk/bcm/clk-bcm2835.c @@ -502,6 +502,8 @@ struct bcm2835_clock_data { bool low_jitter; u32 tcnt_mux; + + bool round_up; }; struct bcm2835_gate_data { @@ -992,12 +994,30 @@ static long bcm2835_clock_rate_from_divisor(struct bcm2835_clock *clock, return temp; } +unsigned long bcm2835_clock_round(unsigned long clk) +{ + unsigned long scaler; + + /* + * If increasing a clock by less than 0.1% changes it + * from ..999.. to ..000.., round up. + */ + scaler = 1; + while (scaler * 100000 < clk) + scaler *= 10; + if ((clk + scaler - 1) / scaler % 1000 == 0) + clk = (clk / scaler + 1) * scaler; + + return clk; +} + static unsigned long bcm2835_clock_get_rate(struct clk_hw *hw, unsigned long parent_rate) { struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw); struct bcm2835_cprman *cprman = clock->cprman; const struct bcm2835_clock_data *data = clock->data; + unsigned long rate; u32 div; if (data->int_bits == 0 && data->frac_bits == 0) @@ -1005,7 +1025,12 @@ static unsigned long bcm2835_clock_get_rate(struct clk_hw *hw, div = cprman_read(cprman, data->div_reg); - return bcm2835_clock_rate_from_divisor(clock, parent_rate, div); + rate = bcm2835_clock_rate_from_divisor(clock, parent_rate, div); + + if (data->round_up) + rate = bcm2835_clock_round(rate); + + return rate; } static void bcm2835_clock_wait_busy(struct bcm2835_clock *clock) @@ -2142,7 +2167,8 @@ static const struct bcm2835_clk_desc clk_desc_array[] = { .div_reg = CM_UARTDIV, .int_bits = 10, .frac_bits = 12, - .tcnt_mux = 28), + .tcnt_mux = 28, + .round_up = true), /* TV encoder clock. Only operating frequency is 108Mhz. */ [BCM2835_CLOCK_VEC] = REGISTER_PER_CLK(
The UART clock is initialised to be as close to the requested frequency as possible without exceeding it. Now that there is a clock manager that returns the actual frequencies, an expected 48MHz clock is reported as 47999625. If the requested baudrate == requested clock/16, there is no headroom and the slight reduction in actual clock rate results in failure. If increasing a clock by less than 0.1% changes it from ..999.. to ..000.., round it up. This is reworked version of a downstream fix: https://github.com/raspberrypi/linux/commit/ab3f1b39537f6d3825b8873006fbe2fc5ff057b7 Cc: Phil Elwell <phil@raspberrypi.org> Signed-off-by: Ivan T. Ivanov <iivanov@suse.de> --- drivers/clk/bcm/clk-bcm2835.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-)