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Fri, 5 Mar 2021 09:42:52 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3030.oracle.com with ESMTP id 3700121a2j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 05 Mar 2021 09:42:52 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 1259goug017448; Fri, 5 Mar 2021 09:42:50 GMT Received: from kadam (/102.36.221.92) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 05 Mar 2021 09:42:49 +0000 Date: Fri, 5 Mar 2021 12:42:42 +0300 From: Dan Carpenter To: Pratyush Yadav Cc: Jay Fang , linux-spi@vger.kernel.org, broonie@kernel.org, huangdaode@huawei.com Subject: Re: [PATCH] spi: cadence-quadspi: Silence shiftTooManyBitsSigned warning Message-ID: <20210305094242.GH2222@kadam> References: <1614854872-8694-1-git-send-email-f.fangjian@huawei.com> <20210304130845.GE2222@kadam> <20210304193427.rdtu75tv6invjq2d@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210304193427.rdtu75tv6invjq2d@ti.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-IMR: 1 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9913 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 mlxscore=0 phishscore=0 malwarescore=0 spamscore=0 mlxlogscore=999 suspectscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103050046 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9913 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 impostorscore=0 suspectscore=0 phishscore=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 clxscore=1011 mlxlogscore=999 adultscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103050046 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org On Fri, Mar 05, 2021 at 01:04:27AM +0530, Pratyush Yadav wrote: > On 04/03/21 04:08PM, Dan Carpenter wrote: > > On Thu, Mar 04, 2021 at 06:47:52PM +0800, Jay Fang wrote: > > > drivers/spi/spi-cadence-quadspi.c:267:18: warning: Shifting signed 32-bit > > > value by 31 bits is undefined behaviour [shiftTooManyBitsSigned] > > > return reg & (1 << CQSPI_REG_CONFIG_IDLE_LSB); > > > ^ > > > > > > Reported-by: kernel test robot > > > Reported-by: Dan Carpenter > > > Signed-off-by: Jay Fang > > > --- > > > drivers/spi/spi-cadence-quadspi.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c > > > index 442cc7c..9a2798a5 100644 > > > --- a/drivers/spi/spi-cadence-quadspi.c > > > +++ b/drivers/spi/spi-cadence-quadspi.c > > > @@ -264,7 +264,7 @@ static bool cqspi_is_idle(struct cqspi_st *cqspi) > > > { > > > u32 reg = readl(cqspi->iobase + CQSPI_REG_CONFIG); > > > > > > - return reg & (1 << CQSPI_REG_CONFIG_IDLE_LSB); > > > + return reg & (1UL << CQSPI_REG_CONFIG_IDLE_LSB); > > > > This is always going to be false because reg is a u32. > > Hmm... I don't see why it would always be false. reg would promoted to > unsigned long and the result should then depend on the actual value of > the bit, which can be represented by an unsigned long. There is no loss > of information. > > Anyway, it still makes more sense to make it 1U because reg is u32. Just > keep the types same and avoid all the conversion rules. Ah, crap. I'm sorry. I somehow thought when I forwarded this bug the other day that CQSPI_REG_CONFIG_IDLE_LSB was more than 31. regards, dan carpenter