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Date: Tue, 10 Jul 2018 13:31:31 +0530
From: Srinath Mannam <srinath.mannam@...adcom.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: wim@...ux-watchdog.org, Ray Jui <ray.jui@...adcom.com>,
Vladimir Olovyannikov <vladimir.olovyannikov@...adcom.com>,
Vikram Prakash <vikram.prakash@...adcom.com>,
Scott Branden <scott.branden@...adcom.com>,
Sudeep Holla <sudeep.holla@....com>,
linux-watchdog@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2] watchdog: sp805: Add clock-frequency property
Hi Guenter,
I missed your comment about "Clearing wdt->clk is useless." I will
remove that line.
Regards,
Srinath.
On Tue, Jul 10, 2018 at 1:27 PM, Srinath Mannam
<srinath.mannam@...adcom.com> wrote:
> Hi Guenter,
>
> Thank you for your feedback. Please find my answers in lined.
>
> On Mon, Jul 9, 2018 at 7:15 PM, Guenter Roeck <linux@...ck-us.net> wrote:
>> On 07/09/2018 03:19 AM, Srinath Mannam wrote:
>>>
>>> When using ACPI node, binding clock devices are
>>> not available as device tree, So clock-frequency
>>> property given in _DSD object of ACPI device is
>>> used to calculate Watchdog rate.
>>>
>>> Signed-off-by: Srinath Mannam <srinath.mannam@...adcom.com>
>>> ---
>>> drivers/watchdog/sp805_wdt.c | 34 ++++++++++++++++++++++++++--------
>>> 1 file changed, 26 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
>>> index 9849db0..ad5ed64 100644
>>> --- a/drivers/watchdog/sp805_wdt.c
>>> +++ b/drivers/watchdog/sp805_wdt.c
>>> @@ -11,6 +11,7 @@
>>> * warranty of any kind, whether express or implied.
>>> */
>>> +#include <linux/acpi.h>
>>> #include <linux/device.h>
>>> #include <linux/resource.h>
>>> #include <linux/amba/bus.h>
>>> @@ -22,6 +23,7 @@
>>> #include <linux/math64.h>
>>> #include <linux/module.h>
>>> #include <linux/moduleparam.h>
>>> +#include <linux/of.h>
>>> #include <linux/pm.h>
>>> #include <linux/slab.h>
>>> #include <linux/spinlock.h>
>>> @@ -65,6 +67,7 @@ struct sp805_wdt {
>>> spinlock_t lock;
>>> void __iomem *base;
>>> struct clk *clk;
>>> + u64 rate;
>>> struct amba_device *adev;
>>> unsigned int load_val;
>>> };
>>> @@ -80,7 +83,7 @@ static int wdt_setload(struct watchdog_device *wdd,
>>> unsigned int timeout)
>>> struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>> u64 load, rate;
>>> - rate = clk_get_rate(wdt->clk);
>>> + rate = wdt->rate;
>>> /*
>>> * sp805 runs counter with given value twice, after the end of
>>> first
>>> @@ -106,9 +109,7 @@ static int wdt_setload(struct watchdog_device *wdd,
>>> unsigned int timeout)
>>> static unsigned int wdt_timeleft(struct watchdog_device *wdd)
>>> {
>>> struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>> - u64 load, rate;
>>> -
>>> - rate = clk_get_rate(wdt->clk);
>>> + u64 load;
>>> spin_lock(&wdt->lock);
>>> load = readl_relaxed(wdt->base + WDTVALUE);
>>> @@ -118,7 +119,7 @@ static unsigned int wdt_timeleft(struct
>>> watchdog_device *wdd)
>>> load += wdt->load_val + 1;
>>> spin_unlock(&wdt->lock);
>>> - return div_u64(load, rate);
>>> + return div_u64(load, wdt->rate);
>>> }
>>> static int
>>> @@ -228,10 +229,27 @@ sp805_wdt_probe(struct amba_device *adev, const
>>> struct amba_id *id)
>>> if (IS_ERR(wdt->base))
>>> return PTR_ERR(wdt->base);
>>> - wdt->clk = devm_clk_get(&adev->dev, NULL);
>>> - if (IS_ERR(wdt->clk)) {
>>> + if (adev->dev.of_node) {
>>> + wdt->clk = devm_clk_get(&adev->dev, NULL);
>>> + if (IS_ERR(wdt->clk)) {
>>> + ret = PTR_ERR(wdt->clk);
>>> + wdt->clk = NULL;
>>
>>
>> Clearing wdt->clk is useless.
>
> If not, clk_prepare_enable and clk_disable_unprepare functions calls
> made in this driver will crash.
Sorry I missed your point. I will remove that.
>
>>
>>> + } else
>>> + wdt->rate = clk_get_rate(wdt->clk);
>>
>>
>> The else branch should be in { } as well per coding style.
> I will add the change.
>>
>>> + } else if (has_acpi_companion(&adev->dev)) {
>>> + /*
>>> + * When Driver probe with ACPI device, clock devices
>>> + * are not available, so watchdog rate get from
>>> + * clock-frequency property given in _DSD object.
>>> + */
>>> + device_property_read_u64(&adev->dev, "clock-frequency",
>>> + &wdt->rate);
>>
>>
>> Continuation line alignment is off.
> I missed it, Thank you, I will make the change.
>>
>> Still not documented. Maybe that is common for ACPI devices nowadays.
>> If so, I'll need at least a pointer to a document or something declaring
>> that ACPI devices do not use well documented properties, and a confirmation
>> that using such properties is acceptable in the Linux kernel.
>>
> patches listed below has same approach to add ACPI support.
> ex:
> 1. commit 515da746983bc6382e380ba8b1ce9345a9550ffe
> Author: Naveen Kaje <nkaje@...eaurora.org>
> Date: Tue Oct 11 10:27:56 2016 -0600
>
> i2c: qup: add ACPI support
>
> 2. commit 82a19035d000c8b4fd7d6f61b614f63dec75d389
> Author: Lendacky, Thomas <Thomas.Lendacky@....com>
> Date: Fri Jan 16 12:47:16 2015 -0600
>
> amd-xgbe: Add ACPI support
>
>>> + if (!wdt->rate)
>>> + ret = -ENODEV;
>>> + }
>>> +
>>> + if (ret) {
>>> dev_warn(&adev->dev, "Clock not found\n");
>>> - ret = PTR_ERR(wdt->clk);
>>> goto err;
>>> }
>>
>>
>> Please move the error handling to where the error occurs. While doing that,
>> please change the message to dev_err() - this is an error, not a warning -
>> and change the second error message to match the error (it did not find
>> the property).
>>
>> Also, return directly - the goto just generates another error message
>> which is ridiculous.
> Thank you, I will add the changes.
>>
>> Thanks,
>> Guenter
>
> Regards,
> Srinath.
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