From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Subject: Re: [PATCH 1/2] spi: Add call to spi_slave_abort() function when spidev driver is released Date: Thu, 26 Sep 2019 09:59:41 +0200 Message-ID: <20190926095941.0615f335@jawa> References: <20190924110547.14770-1-lukma@denx.de> <20190924110547.14770-2-lukma@denx.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; boundary="Sig_/5s0ODXtpIoabspOUcWPgLRh"; protocol="application/pgp-signature" Cc: Mark Brown , linux-spi , Linux Kernel Mailing List , Krzysztof Kozlowski To: Geert Uytterhoeven Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org --Sig_/5s0ODXtpIoabspOUcWPgLRh Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Hi Geert, > Hi Lukasz, >=20 > On Thu, Sep 26, 2019 at 3:33 AM Lukasz Majewski wrote: > > This change is necessary for spidev devices (e.g. /dev/spidev3.0) > > working in the slave mode (like NXP's dspi driver for Vybrid SoC). > > > > When SPI HW works in this mode - the master is responsible for > > providing CS and CLK signals. However, when some fault happens - > > like for example distortion on SPI lines - the SPI Linux driver > > needs a chance to recover from this abnormal situation and prepare > > itself for next (correct) transmission. > > > > This change doesn't pose any threat on drivers working in master > > mode as spi_slave_abort() function checks if SPI slave mode is > > supported. > > > > Signed-off-by: Lukasz Majewski =20 >=20 > Thanks for your patch! >=20 > Yesterday I saw this appear on spi/for-next, but I couldn't find the > email in my mbox. Today it has arrived. Looks like gmail had some > troubles ("Delivered after 138401 seconds", ugh). I've already sent v2 of this patch, as Intel Linux test setup spot the error with lack of #define guards. >=20 > > --- a/drivers/spi/spidev.c > > +++ b/drivers/spi/spidev.c > > @@ -627,6 +627,7 @@ static int spidev_release(struct inode *inode, > > struct file *filp) if (dofree) > > kfree(spidev); > > } > > + spi_slave_abort(spidev->spi); =20 >=20 > Looks good to me. Just wondering if this should be done for the last > user only, i.e. in the "if" block above, like resetting speed_hz? I also thought about this. However, from my use case the user must end the transmission with CTRL+C on his user space program, which in turn communicate via SPI with /dev/spidev3.0. There might be many (potential) programs using the /dev/spidev3.0 at the same time, so the usage count may be not one. For the above reason I've moved it outside the above if(). >=20 > > mutex_unlock(&device_list_lock); > > > > return 0; =20 >=20 > Gr{oetje,eeting}s, >=20 > Geert >=20 Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de --Sig_/5s0ODXtpIoabspOUcWPgLRh Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEgAyFJ+N6uu6+XupJAR8vZIA0zr0FAl2Mb+0ACgkQAR8vZIA0 zr18ogf+Nkm6YALkd0PZS43sKVKplV00GjN15f39tfe1iYqHDzToQk2HTKQgJYFJ q713F216HIdJTpNDTpc+EZkMARIlPAAse5HphE0WIUUk41ZW6Gi038tJtzrgJFRF xkgQSVPFy3mIfheTBenYzYgvF0CKCDl0hOScBsmXoYQ4A6doQXZoniENZp1f3ybc vb+ruj9PjepQyp/jHjYO7KiQC9nPY+azM3qkp8AHkYXY9iN3SnIrFg5hqCE2zSnZ NyCgt+380i6WlXpLua0oxvp5ypxSbufWFkKjIo0mjU67A/cgWe1WUZWCIkrG+J+y Y/g3fKvcaeW6LwWO5Jc67yBQ3HQm2g== =cdef -----END PGP SIGNATURE----- --Sig_/5s0ODXtpIoabspOUcWPgLRh--