Re: [PATCH 2/3] mmc: sdhci-esdhc-imx: obtain the 'per' clock rate after its enablement

From: Ciprian Marian Costea
Date: Wed Jul 10 2024 - 08:51:10 EST


On 7/10/2024 3:33 PM, Adrian Hunter wrote:
On 8/07/24 15:10, Ciprian Costea wrote:
The I.MX SDHCI driver assumes that the frequency of the 'per' clock
can be obtained even on disabled clocks, which is not always the case.

According to 'clk_get_rate' documentation, it is only valid
once the clock source has been enabled.

The kerneldoc comment for clk_get_rate() says

Can be called regardless of the clock enabledness

which sounds like the opposite. Please clarify.


Hello Adrian,

My observation was based on the following [1] 'clk_get_rate()' documentation.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/clk.h#n720

Best Regards,
Ciprian


Signed-off-by: Ciprian Costea <ciprianmarian.costea@xxxxxxxxxxx>
---
drivers/mmc/host/sdhci-esdhc-imx.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 21d984a77be8..8f0bc6dca2b0 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -1709,7 +1709,6 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
}
pltfm_host->clk = imx_data->clk_per;
- pltfm_host->clock = clk_get_rate(pltfm_host->clk);
err = clk_prepare_enable(imx_data->clk_per);
if (err)
goto free_sdhci;
@@ -1720,6 +1719,13 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
if (err)
goto disable_ipg_clk;
+ pltfm_host->clock = clk_get_rate(pltfm_host->clk);
+ if (!pltfm_host->clock) {
+ dev_err(mmc_dev(host->mmc), "could not get clk rate\n");
+ err = -EINVAL;
+ goto disable_ahb_clk;
+ }
+
imx_data->pinctrl = devm_pinctrl_get(&pdev->dev);
if (IS_ERR(imx_data->pinctrl))
dev_warn(mmc_dev(host->mmc), "could not get pinctrl\n");