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Date:   Wed, 31 Mar 2021 21:18:50 +0530
From:   Vinod Koul <vkoul@kernel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Bard Liao <yung-chuan.liao@linux.intel.com>,
        Sanyog Kale <sanyog.r.kale@intel.com>,
        linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org, kernel test robot <lkp@intel.com>
Subject: Re: [PATCH] soundwire: qcom: use signed variable for error return
Message-ID: <YGSZ4sAwMUA5kQsc@vkoul-mobl.Dlink>
References: <20210331072111.2945945-1-vkoul@kernel.org>
 <9cdef4e9-a38a-6c77-1b23-739f85384b12@linux.intel.com>
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On 31-03-21, 09:41, Pierre-Louis Bossart wrote:
> 
> 
> On 3/31/21 2:21 AM, Vinod Koul wrote:
> > We get warning for using a unsigned variable being compared to less than
> > zero. The comparison is correct as it checks for errors from previous
> > call to qcom_swrm_get_alert_slave_dev_num(), so we should use a signed
> > variable instead.
> > 
> > drivers/soundwire/qcom.c: qcom_swrm_irq_handler() warn: impossible
> > condition '(devnum < 0) => (0-255 < 0)'
> > 
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Vinod Koul <vkoul@kernel.org>
> > ---
> >   drivers/soundwire/qcom.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
> > index b08ecb9b418c..55ed133c6704 100644
> > --- a/drivers/soundwire/qcom.c
> > +++ b/drivers/soundwire/qcom.c
> > @@ -428,7 +428,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
> >   	struct qcom_swrm_ctrl *swrm = dev_id;
> >   	u32 value, intr_sts, intr_sts_masked, slave_status;
> >   	u32 i;
> > -	u8 devnum = 0;
> > +	s8 devnum = 0;
> 
> it's not great to store negative error codes with s8. That works in this
> specific case because the function only returns -EINVAL.

Yeah I did check EINVAL was the case which would work but in general I
agree that makes sense, I discussed with Srini on IRC and looks like I
havent posted v2, should hit the pipes shortly

-- 
~Vinod