linux-kernel - RE: [PATCH v2 2/4] spi: spi-fsl-dspi: Fix delete the processing of undefined bitmask for rxdata

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Message-ID: <AM0PR04MB4353FB4E5148D16B1647BA8A97EE0@AM0PR04MB4353.eurprd04.prod.outlook.com>
Date:   Sun, 30 Sep 2018 10:37:13 +0000
From:   Chuanhua Han <chuanhua.han@....com>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
CC:     "broonie@...nel.org" <broonie@...nel.org>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "eha@...f.com" <eha@...f.com>
Subject: RE: [PATCH v2 2/4] spi: spi-fsl-dspi: Fix delete the processing of
 undefined bitmask for rxdata



> -----Original Message-----
> From: Boris Brezillon <boris.brezillon@...tlin.com>
> Sent: 2018年9月30日 18:17
> To: Chuanhua Han <chuanhua.han@....com>
> Cc: broonie@...nel.org; linux-spi@...r.kernel.org;
> linux-kernel@...r.kernel.org; eha@...f.com
> Subject: Re: [PATCH v2 2/4] spi: spi-fsl-dspi: Fix delete the processing of
> undefined bitmask for rxdata
> 
> On Sun, 30 Sep 2018 10:10:14 +0000
> Chuanhua Han <chuanhua.han@....com> wrote:
> 
> > > -----Original Message-----
> > > From: Boris Brezillon <boris.brezillon@...tlin.com>
> > > Sent: 2018年9月30日 18:07
> > > To: Chuanhua Han <chuanhua.han@....com>
> > > Cc: broonie@...nel.org; linux-spi@...r.kernel.org;
> > > linux-kernel@...r.kernel.org; eha@...f.com
> > > Subject: Re: [PATCH v2 2/4] spi: spi-fsl-dspi: Fix delete the
> > > processing of undefined bitmask for rxdata
> > >
> > > On Sun, 30 Sep 2018 17:25:33 +0800
> > > Chuanhua Han <chuanhua.han@....com> wrote:
> > >
> > > > This patch fixes the problem of rxdata being equal to 0 during the
> > > > XSPI mode transfer of the dspi controller.
> > > > In XSPI mode, If it is not deleted, the value of rxdata will be
> > > > equal to 0, and the data received will not be received correctly,
> > > > causing the receiving transfer of the spi to fail.
> > > >
> > > > Signed-off-by: Chuanhua Han <chuanhua.han@....com>
> > > > ---
> > > > Changes in v2:
> > > >  -The original patch is divided into multiple patches(the original
> > > > patch theme is "spi: spi-fsl-dspi: Fix support for XSPI transport
> > > > mode"),one of which is segmented.
> > > >
> > > >  drivers/spi/spi-fsl-dspi.c | 3 ---
> > > >  1 file changed, 3 deletions(-)
> > > >
> > > > diff --git a/drivers/spi/spi-fsl-dspi.c
> > > > b/drivers/spi/spi-fsl-dspi.c index 3082e72e4f6c..4dc1064bf408
> > > > 100644
> > > > --- a/drivers/spi/spi-fsl-dspi.c
> > > > +++ b/drivers/spi/spi-fsl-dspi.c
> > > > @@ -243,9 +243,6 @@ static void dspi_push_rx(struct fsl_dspi
> > > > *dspi, u32
> > > rxdata)
> > > >  	if (!dspi->rx)
> > > >  		return;
> > > >
> > > > -	/* Mask of undefined bits */
> > > > -	rxdata &= (1 << dspi->bits_per_word) - 1;
> > > > -
> > >
> > > Why not
> > In xspi mode, the value of rxdata after the statement is processed is equal to
> 0 no matter what data is received.
> 
> Only if dspi->bits_per_word is 0.
> 
> Actually, I just had a look, and xfer->bits_per_word should never be 0 because
> spi_validate() makes sure it's initialized [1]. Don't know where
> dpsi->bits_per_word comes from, but maybe you have a problem there
> (dpsi->bits_per_word and xfer->bits_per_word not in sync).
> 
> [1]https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Feli
> xir.bootlin.com%2Flinux%2Fv4.19-rc5%2Fsource%2Fdrivers%2Fspi%2Fspi.c%23
> L2869&amp;data=02%7C01%7Cchuanhua.han%40nxp.com%7Cd92a3b54ccf0
> 4d1c1f3208d626bde775%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C
> 0%7C636738994411369491&amp;sdata=piLwfBc0kzMhOnI5uubHYJ9tbe%2BR
> KENKbYiLrkY1c30%3D&amp;reserved=0
OK, Let me analyze it again,Thanks!