The 05/06/2021 18:24, Philipp Zabel wrote:

Hi Steven,

On Thu, May 06, 2021 at 06:03:12PM +0800, Steven Lee wrote:

quoted

For cleaning up the AST2600 eMMC controller, the reset signal should be
asserted and deasserted before it is probed.

Signed-off-by: Steven Lee <redacted>
---
 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

[...]

quoted

@@ -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.

quoted

 	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,

quoted

+	if (!match)
+		return -ENODEV;
+
+	if (match->data)
+		info = match->data;

and info could be set unconditionally as well:

	info = match->data;

quoted

+	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.

quoted

+			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.

quoted

+				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).

quoted

+			}
+		}
+	}
+
 	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