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Date: Tue, 20 Oct 2015 10:39:32 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Shawn Lin <shawn.lin@...k-chips.com>
Cc: Michal Simek <michal.simek@...inx.com>,
Sören Brinkmann <soren.brinkmann@...inx.com>,
linux-mmc <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Kishon <kishon@...com>
Subject: Re: [PATCH v3 2/3] mmc: sdhci-of-arasan: add phy support for sdhci-of-arasan
+ Kishon
On 20 October 2015 at 09:05, Shawn Lin <shawn.lin@...k-chips.com> wrote:
> This patch adds Generic PHY access for sdhci-of-arasan. Driver
> can get PHY handler from dt-binding, and power-on/init the PHY.
> Also we add pm ops for PHY here if CONFIG_PM_SLEEP is enabled.
> Currently, it's just mandatory for arasan,sdhci-5.1.
>
> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
>
> Serise-changes: 3
> - remove phy_init/exit for suspend/resume
> - adjust phy_int/power_on seq to make code more reasonable
> - simplify suspend/resume_phy
>
> Serise-changes: 2
> - Keep phy as a mandatory requirement for arasan,sdhci-5.1
>
> ---
>
> Changes in v2: None
>
> drivers/mmc/host/sdhci-of-arasan.c | 87 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 87 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index 75379cb..85bd0f9d 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -21,6 +21,7 @@
>
> #include <linux/module.h>
> #include <linux/of_device.h>
> +#include <linux/phy/phy.h>
> #include "sdhci-pltfm.h"
>
> #define SDHCI_ARASAN_CLK_CTRL_OFFSET 0x2c
> @@ -35,6 +36,7 @@
> */
> struct sdhci_arasan_data {
> struct clk *clk_ahb;
> + struct phy *phy;
> };
>
> static unsigned int sdhci_arasan_get_timeout_clock(struct sdhci_host *host)
> @@ -70,6 +72,42 @@ static struct sdhci_pltfm_data sdhci_arasan_pdata = {
>
> #ifdef CONFIG_PM_SLEEP
> /**
> + * sdhci_arasan_suspend_phy - Suspend phy method for the driver
> + * @phy: Handler of phy structure
> + * Returns 0 on success and error value on error
> + *
> + * Put the phy in a deactive state.
> + */
> +static int sdhci_arasan_suspend_phy(struct phy *phy)
> +{
> + int ret = 0;
> +
> + ret = phy_power_off(phy);
> + if (ret)
This is an odd error handling, should you really do phy_power_on()?
> + phy_power_on(phy);
> +
> + return ret;
> +}
> +
> +/**
> + * sdhci_arasan_resume_phy - Resume phy method for the driver
> + * @phy: Handler of phy structure
> + * Returns 0 on success and error value on error
> + *
> + * Put the phy in a active state.
> + */
> +static int sdhci_arasan_resume_phy(struct phy *phy)
> +{
> + int ret = 0;
> +
> + ret = phy_power_on(phy);
> + if (ret)
Similar comment as above.
> + phy_power_off(phy);
> +
> + return ret;
> +}
> +
> +/**
> * sdhci_arasan_suspend - Suspend method for the driver
> * @dev: Address of the device structure
> * Returns 0 on success and error value on error
> @@ -88,6 +126,15 @@ static int sdhci_arasan_suspend(struct device *dev)
> if (ret)
> return ret;
>
> + if (!IS_ERR(sdhci_arasan->phy)) {
> + ret = sdhci_arasan_suspend_phy(sdhci_arasan->phy);
> + if (ret) {
> + dev_err(dev, "Cannot suspend phy.\n");
> + sdhci_resume_host(host);
This is an odd error handling, why do sdhci_resume_host()?
> + return ret;
> + }
> + }
> +
> clk_disable(pltfm_host->clk);
> clk_disable(sdhci_arasan->clk_ahb);
>
> @@ -122,6 +169,16 @@ static int sdhci_arasan_resume(struct device *dev)
> return ret;
> }
>
> + if (!IS_ERR(sdhci_arasan->phy)) {
> + ret = sdhci_arasan_resume_phy(sdhci_arasan->phy);
> + if (ret) {
> + dev_err(dev, "Cannot resume phy.\n");
> + clk_disable(sdhci_arasan->clk_ahb);
> + clk_disable(pltfm_host->clk);
> + return ret;
The error handling is starting to be a bit complex in
sdhci_arasan_resume(), perhaps it's time to add some labels to make
the code more readable?
> + }
> + }
> +
> return sdhci_resume_host(host);
> }
> #endif /* ! CONFIG_PM_SLEEP */
> @@ -166,6 +223,33 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
> goto clk_dis_ahb;
> }
>
> + sdhci_arasan->phy = NULL;
NULL isn't an error. You probably want something like:
sdhci_arasan->phy = ERR_PTR(-ENODEV);
Although, I just realize that the phy API works a bit differently than
other APIs. More precisely, instead of returning an error while you
provide a NULL pointer to the APIs, it will treat it as a NOOP and
return a non-error code (at least according to the documentation). I
don't know why the phy API is different, but to me I prefer to use the
regular kernel style and thus, please adopt to my suggestion above.
> + if (of_device_is_compatible(pdev->dev.of_node,
> + "arasan,sdhci-5.1")) {
> + sdhci_arasan->phy = devm_phy_get(&pdev->dev,
> + "phy_arasan");
> + if (IS_ERR(sdhci_arasan->phy)) {
> + ret = -ENODEV;
You should give "ret" the error code from devm_phy_get(), via
PTR_ERR(sdhci_arasan->phy).
> + dev_err(&pdev->dev, "No phy for arasan,sdhci-5.1.\n");
> + goto clk_dis_ahb;
> + }
> +
> + ret = phy_init(sdhci_arasan->phy);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "phy_init err.\n");
> + phy_exit(sdhci_arasan->phy);
phy_exit(), that seems like and odd error handling as the phy_init() failed.
> + goto clk_dis_ahb;
> + }
> +
> + ret = phy_power_on(sdhci_arasan->phy);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "phy_power_on err.\n");
> + phy_power_off(sdhci_arasan->phy);
Similar comment as above.
> + phy_exit(sdhci_arasan->phy);
> + goto clk_dis_ahb;
> + }
> + }
> +
I believe you need at least phy_exit() if a failure occurs after this
point!? Perhaps some new error labels will deal with this nicely!?
> host = sdhci_pltfm_init(pdev, &sdhci_arasan_pdata, 0);
> if (IS_ERR(host)) {
> ret = PTR_ERR(host);
> @@ -210,6 +294,9 @@ static int sdhci_arasan_remove(struct platform_device *pdev)
> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> struct sdhci_arasan_data *sdhci_arasan = pltfm_host->priv;
>
> + if (!IS_ERR(sdhci_arasan->phy))
> + phy_exit(sdhci_arasan->phy);
> +
> clk_disable_unprepare(sdhci_arasan->clk_ahb);
>
> return sdhci_pltfm_unregister(pdev);
> --
> 2.3.7
>
>
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