The 05/06/2021 18:24, Philipp Zabel wrote:
> 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:
>
Will modify it.
> > 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().
>
Will modify as you suggest.
> > + 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?
>
Will return error here.
> > + 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?
>
Per the internal discussion, I Will add udelay(1).
> > + }
> > + }
> > + }
> > +
> > 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.
>
Thanks for the suggestion. I will try to move the implementation of
reset after devm_ioremap_resource().
> regards
> Philipp
