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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id m129sm506802oif.34.2021.03.31.09.24.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Mar 2021 09:24:15 -0700 (PDT) Date: Wed, 31 Mar 2021 11:24:13 -0500 From: Bjorn Andersson To: Vinod Koul Cc: Srinivas Kandagatla , Bard Liao , Pierre-Louis Bossart , Sanyog Kale , linux-arm-msm@vger.kernel.org, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, kernel test robot Subject: Re: [PATCH] soundwire: qcom: use signed variable for error return Message-ID: <20210331162413.GJ904837@yoga> References: <20210331072111.2945945-1-vkoul@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210331072111.2945945-1-vkoul@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Wed 31 Mar 02:21 CDT 2021, 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 > Signed-off-by: Vinod Koul > --- > 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; At least in today's linux-next qcom_swrm_get_alert_slave_dev_num() returns an int and the code only checks to see if this is negative. So it seems like making this a full int ensures there's no truncation etc. And at least as written today there's no need to initialize the variable. Regards, Bjorn > int ret = IRQ_HANDLED; > > swrm->reg_read(swrm, SWRM_INTERRUPT_STATUS, &intr_sts); > -- > 2.26.3 >