Hi Steven,
On Thu, May 06, 2021 at 06:03:12PM +0800, Steven Lee wrote:
> For cleaning up the AST2600 eMMC controller, the reset signal should be
> asserted and deasserted before it is probed.
>
> Signed-off-by: Steven Lee <steven_lee@xxxxxxxxxxxxxx>
> ---
> drivers/mmc/host/sdhci-of-aspeed.c | 49 ++++++++++++++++++++++++------
> 1 file changed, 40 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-aspeed.c
> index 4979f98ffb52..8ef06f32abff 100644
> --- a/drivers/mmc/host/sdhci-of-aspeed.c
> +++ b/drivers/mmc/host/sdhci-of-aspeed.c
[...]
> @@ -533,11 +545,22 @@ static struct platform_driver aspeed_sdhci_driver = {
> .remove = aspeed_sdhci_remove,
> };
>
> +static const struct of_device_id aspeed_sdc_of_match[] = {
> + { .compatible = "aspeed,ast2400-sd-controller", },
> + { .compatible = "aspeed,ast2500-sd-controller", },
> + { .compatible = "aspeed,ast2600-sd-controller", .data = &ast2600_sdc_info},
> + { }
> +};
> +
> +MODULE_DEVICE_TABLE(of, aspeed_sdc_of_match);
> +
> static int aspeed_sdc_probe(struct platform_device *pdev)
>
> {
> struct device_node *parent, *child;
> struct aspeed_sdc *sdc;
> + const struct of_device_id *match = NULL;
> + const struct aspeed_sdc_info *info = NULL;
There is no need to initialize these variables to NULL, see below:
> int ret;
>
> sdc = devm_kzalloc(&pdev->dev, sizeof(*sdc), GFP_KERNEL);
> @@ -546,6 +569,23 @@ static int aspeed_sdc_probe(struct platform_device *pdev)
>
> spin_lock_init(&sdc->lock);
>
> + match = of_match_device(aspeed_sdc_of_match, &pdev->dev);
match is set unconditionally before it is used,
> + if (!match)
> + return -ENODEV;
> +
> + if (match->data)
> + info = match->data;
and info could be set unconditionally as well:
info = match->data;
> + if (info) {
> + if (info->flag & PROBE_AFTER_ASSET_DEASSERT) {
> + sdc->rst = devm_reset_control_get(&pdev->dev, NULL);
Please use devm_reset_control_get_exclusive() or
devm_reset_control_get_optional_exclusive().
> + if (!IS_ERR(sdc->rst)) {
Please just return errors here instead of ignoring them.
The reset_control_get_optional variants return NULL in case the
device node doesn't contain a resets phandle, in case you really
consider this reset to be optional even though the flag is set?
> + reset_control_assert(sdc->rst);
> + reset_control_deassert(sdc->rst);
Is there no need for delays between assertion and deassertion or after
the reset is deasserted?
> + }
> + }
> + }
> +
> sdc->clk = devm_clk_get(&pdev->dev, NULL);
> if (IS_ERR(sdc->clk))
> return PTR_ERR(sdc->clk);
In general, I would assert/deassert the reset only after all resources
are successfully acquired. This might avoid unnecessary resets in case
of probe deferrals.
regards
Philipp
