From mboxrd@z Thu Jan 1 00:00:00 1970 From: "FIXED-TERM Buecheler Konstantin (ETAS-SEC/ECT-Mu)" Subject: can: tcan4x5x: spi bits_per_word issue on Raspberry PI Date: Wed, 14 Aug 2019 09:43:21 +0000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Return-path: Content-Language: de-DE Sender: netdev-owner@vger.kernel.org To: "linux-can@vger.kernel.org" , "netdev@vger.kernel.org" Cc: Dan Murphy List-Id: linux-can.vger.kernel.org Hi all, I am trying to use a tcan4550 together with a Raspberry PI 3 B. I am using = the tcan4x5x driver from net-next.=20 I always get the following error during startup. tcan4x5x spi0.0: Probe failed, err=3D-22 tcan4x5x: probe of spi0.0 failed with error -22 I realized that this happens because the Raspberry PI does only support 8/9= bit words. https://elinux.org/index.php?title=3DRPi_SPI#Supported_bits_per= _word In the driver it is set to 32. spi->bits_per_word =3D 32; Setting this to 8 does not help of course since the tcan chip expects a mul= tiple of 32 per spi transaction.=20 I don't know if this is a Raspberry Pi specific problem or if there are mor= e devices with this hardware limitation.=20 Does anyone have a workaround for that?=20 If this a common issue it might be a good idea to patch the driver. I will = check if I can find proper a way to do so.=20 Regards,=20 Konstantin=20