Re: [PATCH] leds: sun50i-a100: avoid division-by-zero warning
From: Guo Ren <guoren@kernel.org>
Date: 2023-12-13 01:26:20
Also in:
linux-leds, linux-sunxi, lkml, llvm
On Wed, Dec 13, 2023 at 5:45 AM Arnd Bergmann [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Arnd Bergmann <arnd@arndb.de> When CONFIG_COMMON_CLK is disabled, e.g. on an x86 randconfig compile test, clang reports a field overflow from propagating the result of a division by zero: drivers/leds/leds-sun50i-a100.c:309:12: error: call to '__compiletime_assert_265' declared with 'error' attribute: FIELD_PREP: value too large for the field control = FIELD_PREP(LEDC_T01_TIMING_CTRL_REG_T1H, timing->t1h_ns / cycle_ns) | Avoid the problem by adding an explicit check for the zero value here. Alternatively the assertion could be avoided with a Kconfig dependency on COMMON_CLK. Fixes: 090a25ad9798 ("leds: sun50i-a100: New driver for the A100 LED controller") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/leds/leds-sun50i-a100.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)diff --git a/drivers/leds/leds-sun50i-a100.c b/drivers/leds/leds-sun50i-a100.c index e4a7e692a908..171cefd1ea0d 100644 --- a/drivers/leds/leds-sun50i-a100.c +++ b/drivers/leds/leds-sun50i-a100.c@@ -303,9 +303,13 @@ static void sun50i_a100_ledc_set_timing(struct sun50i_a100_ledc *priv) { const struct sun50i_a100_ledc_timing *timing = &priv->timing; unsigned long mod_freq = clk_get_rate(priv->mod_clk); - u32 cycle_ns = NSEC_PER_SEC / mod_freq; + u32 cycle_ns; u32 control; + if (!mod_freq) + return; +
Shall we need err_disable_bus_clk?
+ static int sun50i_a100_ledc_set_timing(struct sun50i_a100_ledc *priv)
- static void sun50i_a100_ledc_set_timing(struct sun50i_a100_ledc *priv)
{
const struct sun50i_a100_ledc_timing *timing = &priv->timing;
unsigned long mod_freq = clk_get_rate(priv->mod_clk);
- u32 cycle_ns = NSEC_PER_SEC / mod_freq;
+ u32 cycle_ns;
u32 control;
+ if (!mod_freq)
+ return -EINVAL;
+ cycle_ns = NSEC_PER_SEC / mod_freq;
control = FIELD_PREP(LEDC_T01_TIMING_CTRL_REG_T1H,
timing->t1h_ns / cycle_ns) |
FIELD_PREP(LEDC_T01_TIMING_CTRL_REG_T1L,
timing->t1l_ns / cycle_ns) |
FIELD_PREP(LEDC_T01_TIMING_CTRL_REG_T0H,
timing->t0h_ns / cycle_ns) |
...
return 0;
----------
+ ret = sun50i_a100_ledc_set_timing(priv);
+ if (ret)
+ goto err_disable_bus_clk;
-- 2.39.2
-- Best Regards Guo Ren _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel