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Message-ID: <CABe79T4qj6SaZJzTn_ZY7XfGkj_z6JJ57+WfMm3zGE7XLbT4Lg@mail.gmail.com>
Date: Tue, 10 Jul 2018 13:27:55 +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,
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.
>
>> + } 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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