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Message-ID: <56D97BA8.7090302@intel.com>
Date: Fri, 4 Mar 2016 14:12:24 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Shawn Lin <shawn.lin@...k-chips.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Michal Simek <michal.simek@...inx.com>,
soren.brinkmann@...inx.com, linux-mmc@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [RESEND PATCH v5 2/2] mmc: sdhci-of-arasan: add phy support for
sdhci-of-arasan
On 04/03/16 12:24, Shawn Lin wrote:
> Hi Adrian,
>
> On 2016/3/4 17:14, Adrian Hunter wrote:
>> On 19/02/16 04:20, Shawn Lin wrote:
>>> This patch adds Generic PHY access for sdhci-of-arasan. Driver
>
> [...]
>
>>> /**
>>> * sdhci_arasan_suspend - Suspend method for the driver
>>> * @dev: Address of the device structure
>>> - * Returns 0 on success and error value on error
>>> + * Return: 0 on success and error value on error
>>
>> Really should be a separate patch for the comment fixes.
>
> yep, I won't touch it when I rebase my patch for this topic.
>
>>
>>> *
>>> * Put the device in a low power state.
>>> */
>>> @@ -88,6 +91,14 @@ static int sdhci_arasan_suspend(struct device *dev)
>>> if (ret)
>>> return ret;
>>>
>>> + if (!IS_ERR(sdhci_arasan->phy)) {
>>> + ret = phy_power_off(sdhci_arasan->phy);
>>> + if (ret) {
>>> + dev_err(dev, "Cannot power off phy.\n");
>>
>> I would expect you ought to call sdhci_resume_host() here.
>
> oh, got it.
>
>>
>>> + return ret;
>>> + }
>>> + }
>>> +
>>> clk_disable(pltfm_host->clk);
>>> clk_disable(sdhci_arasan->clk_ahb);
>>>
>>> @@ -97,7 +108,7 @@ static int sdhci_arasan_suspend(struct device *dev)
>>> /**
>>> * sdhci_arasan_resume - Resume method for the driver
>>> * @dev: Address of the device structure
>>> - * Returns 0 on success and error value on error
>>> + * Return: 0 on success and error value on error
>>> *
>>> * Resume operation after suspend
>>> */
>>> @@ -118,11 +129,24 @@ static int sdhci_arasan_resume(struct device *dev)
>>> ret = clk_enable(pltfm_host->clk);
>>> if (ret) {
>>> dev_err(dev, "Cannot enable SD clock.\n");
>>> - clk_disable(sdhci_arasan->clk_ahb);
>>> - return ret;
>>> + goto err_clk_en;
>>> + }
>>> +
>>> + if (!IS_ERR(sdhci_arasan->phy)) {
>>> + ret = phy_power_on(sdhci_arasan->phy);
>>> + if (ret) {
>>> + dev_err(dev, "Cannot power on phy.\n");
>>> + goto err_phy_power;
>>> + }
>>> }
>>>
>>> return sdhci_resume_host(host);
>>> +
>>> +err_phy_power:
>>> + clk_disable(pltfm_host->clk);
>>> +err_clk_en:
>>> + clk_disable(sdhci_arasan->clk_ahb);
>>
>> I don't know that disabling clocks is necessarily the right thing to do if
>> the resume fails. You might want to consider what happens if the system
>> tries to use the device when it is in that state. It's been a long time
>> since I did any ARM work but aren't you risking bus errors. Might just as
>> well not bother and save a few lines of code.
>>
>
> Firstly, I really just follow the orginal err handle.
> It's risking bus errors if disabling ahb clk, but ahb clk is most very
> likely to shared by many controllers. So regarding to the clk reference
> count, the ahb_clk is not *really* disabled and just decrease the
> reference count. How about keep these handles here?
I would remove the error handling on the grounds that it does not do
anything useful.
>
>
>>> + return ret;
>>> }
>>> #endif /* ! CONFIG_PM_SLEEP */
>>>
>>> @@ -183,6 +207,30 @@ static int sdhci_arasan_probe(struct platform_device
>>> *pdev)
>>> goto clk_disable_all;
>>> }
>>>
>>> + sdhci_arasan->phy = ERR_PTR(-ENODEV);
>>> + 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 = PTR_ERR(sdhci_arasan->phy);
>>> + dev_err(&pdev->dev, "No phy for arasan,sdhci-5.1.\n");
>>> + goto clk_disable_all;
>>> + }
>>> +
>>> + ret = phy_init(sdhci_arasan->phy);
>>> + if (ret < 0) {
>>> + dev_err(&pdev->dev, "phy_init err.\n");
>>> + goto clk_disable_all;
>>> + }
>>> +
>>> + ret = phy_power_on(sdhci_arasan->phy);
>>> + if (ret < 0) {
>>> + dev_err(&pdev->dev, "phy_power_on err.\n");
>>> + goto err_phy_power;
>>> + }
>>> + }
>>> +
>>> ret = sdhci_add_host(host);
>>> if (ret)
>>> goto err_pltfm_free;
>>> @@ -190,7 +238,12 @@ static int sdhci_arasan_probe(struct platform_device
>>> *pdev)
>>> return 0;
>>>
>>> err_pltfm_free:
>>> + if (!IS_ERR(sdhci_arasan->phy))
>>> + phy_power_off(sdhci_arasan->phy);
>>> sdhci_pltfm_free(pdev);
>>> +err_phy_power:
>>> + if (!IS_ERR(sdhci_arasan->phy))
>>
>> Looks like you are using sdhci_arasan after it has been free'd by
>> sdhci_pltfm_free().
>>
>> Also there seem to be cases where sdhci_arasan_probe() can exit after
>> sdhci_pltfm_init() without calling sdhci_pltfm_free().
>
> Good catch, will fix it.
>
>>
>>> + phy_exit(sdhci_arasan->phy);
>>> clk_disable_all:
>>> clk_disable_unprepare(clk_xin);
>>> clk_dis_ahb:
>>> @@ -205,6 +258,11 @@ 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_power_off(sdhci_arasan->phy);
>>> + phy_exit(sdhci_arasan->phy);
>>> + }
>>> +
>>
>> When you re-base, take care to keep this chunk above
>> sdhci_pltfm_unregister().
>
> sure.
>
> Thanks for reviewing it.
>
>>
>>> clk_disable_unprepare(sdhci_arasan->clk_ahb);
>>>
>>> return sdhci_pltfm_unregister(pdev);
>>>
>>
>>
>>
>>
>
>
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