From: Philipp Zabel <p.zabel@pengutronix.de>
To: Steven Lee <steven_lee@aspeedtech.com>
Cc: Andrew Jeffery <andrew@aj.id.au>,
Ulf Hansson <ulf.hansson@linaro.org>,
Rob Herring <robh+dt@kernel.org>, Joel Stanley <joel@jms.id.au>,
Adrian Hunter <adrian.hunter@intel.com>,
Ryan Chen <ryanchen.aspeed@gmail.com>,
"moderated list:ASPEED SD/MMC DRIVER"
<linux-aspeed@lists.ozlabs.org>,
"moderated list:ASPEED SD/MMC DRIVER" <openbmc@lists.ozlabs.org>,
"open list:ASPEED SD/MMC DRIVER" <linux-mmc@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"moderated list:ARM/ASPEED MACHINE SUPPORT"
<linux-arm-kernel@lists.infradead.org>,
open list <linux-kernel@vger.kernel.org>,
Hongweiz@ami.com, ryan_chen@aspeedtech.com,
chin-ting_kuo@aspeedtech.com
Subject: Re: [PATCH v3 5/5] mmc: sdhci-of-aspeed: Assert/Deassert reset signal before probing eMMC
Date: Thu, 6 May 2021 12:24:58 +0200 [thread overview]
Message-ID: <20210506102458.GA20777@pengutronix.de> (raw)
In-Reply-To: <20210506100312.1638-6-steven_lee@aspeedtech.com>
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@aspeedtech.com>
> ---
> 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
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-05-06 10:28 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 10:03 [PATCH v3 0/5] mmc: sdhci-of-aspeed: Support toggling SD bus signal Steven Lee
2021-05-06 10:03 ` [PATCH v3 1/5] dt-bindings: mmc: sdhci-of-aspeed: Add an example for AST2600-A2 EVB Steven Lee
2021-05-07 1:13 ` Rob Herring
2021-05-07 3:13 ` Steven Lee
2021-05-07 17:21 ` Rob Herring
2021-05-10 2:32 ` Steven Lee
2021-05-06 10:03 ` [PATCH v3 2/5] ARM: dts: aspeed: ast2600evb: Add comment for gpio regulator of sdhci Steven Lee
2021-05-07 1:40 ` Andrew Jeffery
2021-05-07 3:30 ` Steven Lee
2021-05-07 3:42 ` Andrew Jeffery
2021-05-06 10:03 ` [PATCH v3 3/5] ARM: dts: aspeed: ast2600evb: Add phase correction for emmc controller Steven Lee
2021-05-07 1:34 ` Andrew Jeffery
2021-05-06 10:03 ` [PATCH v3 4/5] mmc: sdhci-of-aspeed: Add a helper for updating capability register Steven Lee
2021-05-07 2:13 ` Andrew Jeffery
2021-05-07 6:59 ` Steven Lee
2021-05-07 7:07 ` Andrew Jeffery
2021-05-06 10:03 ` [PATCH v3 5/5] mmc: sdhci-of-aspeed: Assert/Deassert reset signal before probing eMMC Steven Lee
2021-05-06 10:24 ` Philipp Zabel [this message]
2021-05-07 1:32 ` Andrew Jeffery
2021-05-07 6:24 ` Steven Lee
2021-05-07 7:36 ` Andrew Jeffery
2021-05-10 6:03 ` Steven Lee
2021-05-13 0:42 ` Andrew Jeffery
2021-05-14 2:09 ` Steven Lee
2021-05-14 2:37 ` Andrew Jeffery
2021-05-19 10:57 ` Steven Lee
2021-05-19 23:09 ` Andrew Jeffery
2021-05-07 6:02 ` Steven Lee
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210506102458.GA20777@pengutronix.de \
--to=p.zabel@pengutronix.de \
--cc=Hongweiz@ami.com \
--cc=adrian.hunter@intel.com \
--cc=andrew@aj.id.au \
--cc=chin-ting_kuo@aspeedtech.com \
--cc=devicetree@vger.kernel.org \
--cc=joel@jms.id.au \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-aspeed@lists.ozlabs.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=openbmc@lists.ozlabs.org \
--cc=robh+dt@kernel.org \
--cc=ryan_chen@aspeedtech.com \
--cc=ryanchen.aspeed@gmail.com \
--cc=steven_lee@aspeedtech.com \
--cc=ulf.hansson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).