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Date: Mon, 17 Mar 2014 11:51:22 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Tomasz Figa <t.figa@...sung.com>
Cc: myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
rafael.j.wysocki@...el.com, nm@...com, b.zolnierkie@...saung.com,
pawel.moll@....com, mark.rutland@....com, swarren@...dotorg.org,
ijc+devicetree@...lion.org.uk, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
devicetree@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCHv2 3/8] devfreq: exynos4: Add ppmu's clock control and code
clean about regulator control
Hi Tomasz,
On 03/15/2014 02:42 AM, Tomasz Figa wrote:
> Hi Chanwoo,
>
> On 13.03.2014 09:17, Chanwoo Choi wrote:
>> There are not the clock controller of ppmudmc0/1. This patch control the clock
>> of ppmudmc0/1 which is used for monitoring memory bus utilization.
>>
>> Also, this patch code clean about regulator control and free resource
>> when calling exit/remove function.
>>
>> For example,
>> busfreq@...A0000 {
>> compatible = "samsung,exynos4x12-busfreq";
>>
>> /* Clock for PPMUDMC0/1 */
>> clocks = <&clock CLK_PPMUDMC0>, <&clock CLK_PPMUDMC1>;
>> clock-names = "ppmudmc0", "ppmudmc1";
>>
>> /* Regulator for MIF/INT block */
>> vdd_mif-supply = <&buck1_reg>;
>> vdd_int-supply = <&buck3_reg>;
>> };
>>
>> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
>> ---
>> drivers/devfreq/exynos/exynos4_bus.c | 114 ++++++++++++++++++++++++++++++-----
>> 1 file changed, 100 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/devfreq/exynos/exynos4_bus.c b/drivers/devfreq/exynos/exynos4_bus.c
>> index 1a0effa..a2a3a47 100644
>> --- a/drivers/devfreq/exynos/exynos4_bus.c
>> +++ b/drivers/devfreq/exynos/exynos4_bus.c
>> @@ -62,6 +62,11 @@ enum exynos_ppmu_idx {
>> PPMU_END,
>> };
>>
>> +static const char *exynos_ppmu_clk_name[] = {
>> + [PPMU_DMC0] = "ppmudmc0",
>> + [PPMU_DMC1] = "ppmudmc1",
>> +};
>> +
>> #define EX4210_LV_MAX LV_2
>> #define EX4x12_LV_MAX LV_4
>> #define EX4210_LV_NUM (LV_2 + 1)
>> @@ -86,6 +91,7 @@ struct busfreq_data {
>> struct regulator *vdd_mif; /* Exynos4412/4212 only */
>> struct busfreq_opp_info curr_oppinfo;
>> struct exynos_ppmu ppmu[PPMU_END];
>> + struct clk *clk_ppmu[PPMU_END];
>>
>> struct notifier_block pm_notifier;
>> struct mutex lock;
>> @@ -722,8 +728,26 @@ static int exynos4_bus_get_dev_status(struct device *dev,
>> static void exynos4_bus_exit(struct device *dev)
>> {
>> struct busfreq_data *data = dev_get_drvdata(dev);
>> + int i;
>> +
>> + /*
>> + * Un-map memory map and disable regulator/clocks
>> + * to prevent power leakage.
>> + */
>> + regulator_disable(data->vdd_int);
>> + if (data->type == TYPE_BUSF_EXYNOS4x12)
>> + regulator_disable(data->vdd_mif);
>> +
>> + for (i = 0; i < PPMU_END; i++) {
>> + if (data->clk_ppmu[i])
>
> This check is invalid. Clock pointers must be checked for validity using the IS_ERR() macro, because NULL is a valid clock pointer value indicating a dummy clock.
OK, I'll check it by using the IS_ERR() macro as following:
if (IS_ERR(data->clk_ppmu[i]) {
>
>> + clk_disable_unprepare(data->clk_ppmu[i]);
>> + }
>>
>> - devfreq_unregister_opp_notifier(dev, data->devfreq);
>> + for (i = 0; i < PPMU_END; i++) {
>> + if (data->ppmu[i].hw_base)
>
> Can this even happen? Is there a PPMU without registers?
>
>> + iounmap(data->ppmu[i].hw_base);
>> +
>> + }
>> }
>>
>> static struct devfreq_dev_profile exynos4_devfreq_profile = {
>> @@ -987,6 +1011,7 @@ static int exynos4_busfreq_parse_dt(struct busfreq_data *data)
>> {
>> struct device *dev = data->dev;
>> struct device_node *np = dev->of_node;
>> + const char **clk_name = exynos_ppmu_clk_name;
>> int i, ret;
>>
>> if (!np) {
>> @@ -1005,8 +1030,70 @@ static int exynos4_busfreq_parse_dt(struct busfreq_data *data)
>> }
>> }
>>
>> + /*
>> + * Get PPMU's clocks to control them. But, if PPMU's clocks
>> + * is default 'pass' state, this driver don't need control
>> + * PPMU's clock.
>> + */
>> + for (i = 0; i < PPMU_END; i++) {
>> + data->clk_ppmu[i] = devm_clk_get(dev, clk_name[i]);
>> + if (IS_ERR_OR_NULL(data->clk_ppmu[i])) {
>
> Again, this check is invalid. Only IS_ERR() is the correct way to check whether returned clock pointer is valid.
ditto.
if (IS_ERR(data->clk_ppmu[i]) {
>
>> + dev_warn(dev, "Cannot get %s clock\n", clk_name[i]);
>> + data->clk_ppmu[i] = NULL;
>
> This assignment is wrong. To allow further checking whether the clock was found the value returned from devm_clk_get() must be retained and then IS_ERR() used in further code.
>
> However, I believe it should be an error if a clock is not provided. The driver must make sure that PPMU clocks are ungated before trying to access them, otherwise the system might hang.
OK, I'll use IS_ERR() macro when checking / handling clock instance of 'data->clk_ppmu[i]'.
And If this driver can't get the clock of ppmu, handel error exception.
>
>> + }
>> +
>> + ret = clk_prepare_enable(data->clk_ppmu[i]);
>
> The code above allows the clock to be skipped, but this line doesn't check whether it is valid. Still, I think the clock should be always required.
OK, I'll require clock of ppmu without exception.
>
>> + if (ret < 0) {
>> + dev_warn(dev, "Cannot enable %s clock\n", clk_name[i]);
>> + data->clk_ppmu[i] = NULL;
>> + goto err_clocks;
>> + }
>> + }
>> +
>> + /* Get regulator to control voltage of int block */
>> + data->vdd_int = devm_regulator_get(dev, "vdd_int");
>> + if (IS_ERR(data->vdd_int)) {
>> + dev_err(dev, "Failed to get the regulator of vdd_int\n");
>> + ret = PTR_ERR(data->vdd_int);
>> + goto err_clocks;
>> + }
>> + ret = regulator_enable(data->vdd_int);
>> + if (ret < 0) {
>> + dev_err(dev, "Failed to enable regulator of vdd_int\n");
>> + goto err_clocks;
>> + }
>> +
>> + switch (data->type) {
>> + case TYPE_BUSF_EXYNOS4210:
>> + break;
>> + case TYPE_BUSF_EXYNOS4x12:
>> + /* Get regulator to control voltage of mif blk if Exynos4x12 */
>> + data->vdd_mif = devm_regulator_get(dev, "vdd_mif");
>> + if (IS_ERR(data->vdd_mif)) {
>> + dev_err(dev, "Failed to get the regulator vdd_mif\n");
>> + ret = PTR_ERR(data->vdd_mif);
>> + goto err_regulator;
>> + }
>> + ret = regulator_enable(data->vdd_mif);
>> + if (ret < 0) {
>> + dev_err(dev, "Failed to enable regulator of vdd_mif\n");
>> + goto err_regulator;
>> + }
>> + break;
>> + default:
>> + dev_err(dev, "Unknown device type : %d\n", data->type);
>> + return -EINVAL;
>> + };
>> +
>> return 0;
>>
>> +err_regulator:
>> + regulator_disable(data->vdd_int);
>> +err_clocks:
>> + for (i = 0; i < PPMU_END; i++) {
>> + if (data->clk_ppmu[i])
>
> Invalid check.
Modify it as following:
if (!IS_ERR(data->clk_ppmu[i]) {
Best Regards,
Chanwoo Choi
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