linux-kernel - Re: [PATCH v3 04/15] can: grcan: Add clock handling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <c63eb30b-5856-4fc5-84e1-78e07125f0e7@gaisler.com>
Date: Tue, 27 Jan 2026 14:27:38 +0100
From: Arun Muthusamy <arun.muthusamy@...sler.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 mailhol@...nel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-can@...r.kernel.org,
 Daniel Hellstrom <daniel@...sler.com>
Subject: Re: [PATCH v3 04/15] can: grcan: Add clock handling


On 1/23/26 14:44, Marc Kleine-Budde wrote:
> On 22.01.2026 13:10:27, Arun Muthusamy wrote:
>> From: Daniel Hellstrom <daniel@...sler.com>
>>
>> Add clock handling and add error messages for missing 'freq' DT property.
>>
>> Signed-off-by: Daniel Hellstrom <daniel@...sler.com>
>> Signed-off-by: Arun Muthusamy <arun.muthusamy@...sler.com>
>> ---
>>   drivers/net/can/grcan.c | 19 ++++++++++++++++---
>>   1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c
>> index 3b1b09943436..538a9b4f82ab 100644
>> --- a/drivers/net/can/grcan.c
>> +++ b/drivers/net/can/grcan.c
>> @@ -34,7 +34,7 @@
>>   #include <linux/spinlock.h>
>>   #include <linux/of.h>
>>   #include <linux/of_irq.h>
>> -
>> +#include <linux/clk.h>
>>   #include <linux/dma-mapping.h>
>>
>>   #define DRV_NAME	"grcan"
>> @@ -1644,6 +1644,7 @@ static int grcan_probe(struct platform_device *ofdev)
>>   {
>>   	struct device_node *np = ofdev->dev.of_node;
>>   	struct device_node *sysid_parent;
>> +	struct clk *clk;
>>   	u32 sysid, ambafreq;
>>   	int irq, err;
>>   	void __iomem *base;
>> @@ -1663,8 +1664,20 @@ static int grcan_probe(struct platform_device *ofdev)
>>
>>   	err = of_property_read_u32(np, "freq", &ambafreq);
>>   	if (err) {
>> -		dev_err(&ofdev->dev, "unable to fetch \"freq\" property\n");
>> -		goto exit_error;
>> +		clk = devm_clk_get(&ofdev->dev, NULL);
>> +		if (IS_ERR(clk)) {
>> +			dev_err_probe(&ofdev->dev, PTR_ERR(clk),
>> +				      "Failed both to get \"freq\" property and clock for fallback\n");
>> +			err = PTR_ERR(clk);
>> +			goto exit_error;
>> +		}
> I think devm_clk_get() either returns an error pointer or a valid clock
> pointer.
>
>> +		if (clk) {
>> +			ambafreq = clk_get_rate(clk);
>> +			if (!ambafreq) {
>> +				dev_err(&ofdev->dev, "Invalid or Uninitialized clock\n");
>> +				return -EINVAL;
>> +			}
>> +		}
>>   	}
>>
>>   	base = devm_platform_ioremap_resource(ofdev, 0);
>>
you are correct, since devm_clk_get() returns either a valid clock pointer or an error pointer, "if (clk)" check is indeed redundant.