Re: [PATCH v3 1/6] media: mt9p031: Read back the real clock rate
From: Sakari Ailus <sakari.ailus@linux.intel.com>
Date: 2021-07-05 07:13:54
Also in:
linux-media, lkml
Hi Enrico, On Fri, Jul 02, 2021 at 11:59:17AM +0200, Stefan Riedmueller wrote:
From: Enrico Scholz <redacted> The real and requested clock can differ and because it is used to calculate PLL values, the real clock rate should be read.
Do you have a system where this happens? That suggests there's a wrong value in DT. The preference nowadays is to rely on assigned-clock-rates, even though it's inherently somewhat unreliable, just as clk_set_rate(). This is an existing driver though. The old ones could be kept for compatibility with older DT binaries.
quoted hunk ↗ jump to hunk
Signed-off-by: Enrico Scholz <redacted> Signed-off-by: Stefan Riedmueller <redacted> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- drivers/media/i2c/mt9p031.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c index 77567341ec98..3eaaa8d44523 100644 --- a/drivers/media/i2c/mt9p031.c +++ b/drivers/media/i2c/mt9p031.c@@ -255,6 +255,7 @@ static int mt9p031_clk_setup(struct mt9p031 *mt9p031) struct i2c_client *client = v4l2_get_subdevdata(&mt9p031->subdev); struct mt9p031_platform_data *pdata = mt9p031->pdata; + unsigned long ext_freq; int ret; mt9p031->clk = devm_clk_get(&client->dev, NULL);@@ -265,13 +266,15 @@ static int mt9p031_clk_setup(struct mt9p031 *mt9p031) if (ret < 0) return ret; + ext_freq = clk_get_rate(mt9p031->clk); + /* If the external clock frequency is out of bounds for the PLL use the * pixel clock divider only and disable the PLL. */ - if (pdata->ext_freq > limits.ext_clock_max) { + if (ext_freq > limits.ext_clock_max) { unsigned int div; - div = DIV_ROUND_UP(pdata->ext_freq, pdata->target_freq); + div = DIV_ROUND_UP(ext_freq, pdata->target_freq); div = roundup_pow_of_two(div) / 2; mt9p031->clk_div = min_t(unsigned int, div, 64);@@ -280,7 +283,7 @@ static int mt9p031_clk_setup(struct mt9p031 *mt9p031) return 0; } - mt9p031->pll.ext_clock = pdata->ext_freq; + mt9p031->pll.ext_clock = ext_freq; mt9p031->pll.pix_clock = pdata->target_freq; mt9p031->use_pll = true;
-- Kind regards, Sakari Ailus