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Subject: Re: [PATCH] soc/tegra: fuse: Add clock error check in
 tegra_fuse_readl
To:     Jon Hunter <jonathanh@nvidia.com>, <thierry.reding@gmail.com>,
        <kishon@ti.com>
CC:     <linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <1566991129-13479-1-git-send-email-nkristam@nvidia.com>
 <95734aa4-c7cb-17a2-fa4c-416a5a40b3e6@nvidia.com>
From:   Nagarjuna Kristam <nkristam@nvidia.com>
Message-ID: <282de63e-6a0f-349f-0df9-a6a54cab6ea3@nvidia.com>
Date:   Tue, 3 Sep 2019 10:29:24 +0530
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On 02-09-2019 16:15, Jon Hunter wrote:
> 
> On 28/08/2019 12:18, Nagarjuna Kristam wrote:
>> Tegra fuse clock handle is retrieved in tegra_fuse_probe().
>> tegra_fuse_readl() is exported symbol, which can be called from drivers
>> at any time. tegra_fuse_readl() enables fuse clock and reads corresponding
>> fuse register offset.
>>
>> Calling tegra_fuse_readl() before tegra_fuse_probe(), will cause data
>> abort. Add DEFER_PROBE error check for fuse clock in tegra_fuse_readl(),
>> to avoid enabling of fuse clock, before clock is available.
>>
>> Signed-off-by: Nagarjuna Kristam <nkristam@nvidia.com>
>> ---
>>  drivers/soc/tegra/fuse/fuse-tegra.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/soc/tegra/fuse/fuse-tegra.c b/drivers/soc/tegra/fuse/fuse-tegra.c
>> index 3eb44e6..21b39b7 100644
>> --- a/drivers/soc/tegra/fuse/fuse-tegra.c
>> +++ b/drivers/soc/tegra/fuse/fuse-tegra.c
>> @@ -186,7 +186,7 @@ u32 __init tegra_fuse_read_early(unsigned int offset)
>>  
>>  int tegra_fuse_readl(unsigned long offset, u32 *value)
>>  {
>> -	if (!fuse->read)
>> +	if (!fuse->read || (PTR_ERR(fuse->clk) == -EPROBE_DEFER))
>>  		return -EPROBE_DEFER;
> 
> What about the case where fuse->clk is NULL or a different error value?
> 
> Jon
> 
Yes, all error checks are needed, will use IS_ERR as a separate condition for clock.

Thanks,
Nagarjuna