> -----Original Message----- > From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> > Sent: 2019年4月11日 14:39 > To: Joakim Zhang <qiangqing.zhang@xxxxxxx>; wg@xxxxxxxxxxxxxx; > davem@xxxxxxxxxxxxx > Cc: dl-linux-imx <linux-imx@xxxxxxx>; linux-can@xxxxxxxxxxxxxxx; > netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [EXT] Re: [PATCH] can: dev: clean up CAN ctrlmode when close > CAN device > > On 4/11/19 3:16 AM, Joakim Zhang wrote: > >> Whatever mode you enable via user space use user space to disable > >> them again. > > > > Thank you for your detailed explanation. But in flexcan driver, it > > just set register bit when mode on and do not clear register bit when > > mode off, e.g. loopback, listennoly, 3 samples.... > > Let's see: > > > reg = priv->read(®s->ctrl); > > The ctrl reg is read > > > reg &= ~(FLEXCAN_CTRL_PRESDIV(0xff) | > > FLEXCAN_CTRL_RJW(0x3) | > > FLEXCAN_CTRL_PSEG1(0x7) | > > FLEXCAN_CTRL_PSEG2(0x7) | > > FLEXCAN_CTRL_PROPSEG(0x7) | > > FLEXCAN_CTRL_LPB | > > FLEXCAN_CTRL_SMP | > > FLEXCAN_CTRL_LOM); > > ....the loopback mode, 3 sample mode and listen only mode bits are masked > out.... > > > reg |= FLEXCAN_CTRL_PRESDIV(bt->brp - 1) | > > FLEXCAN_CTRL_PSEG1(bt->phase_seg1 - 1) | > > FLEXCAN_CTRL_PSEG2(bt->phase_seg2 - 1) | > > FLEXCAN_CTRL_RJW(bt->sjw - 1) | > > FLEXCAN_CTRL_PROPSEG(bt->prop_seg - 1); > > > > if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) > > reg |= FLEXCAN_CTRL_LPB; > > if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) > > reg |= FLEXCAN_CTRL_LOM; > > if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES) > > reg |= FLEXCAN_CTRL_SMP; > > ...and the bits are set, if enabled by user space... > > > netdev_dbg(dev, "writing ctrl=0x%08x\n", reg); > > priv->write(reg, ®s->ctrl); > > ...and written to the register. > > So all three bits will be unset, if unset by user space, right? Oh, I see. Thank you! Best Regards, Joakim Zhang > > > When we configure mode off after configured mode on in the user space, > > corresponding bit will not change. Is this should be improved in > > flexcan driver? > > That should work. If it doesn't work, we need a fix. > > regards, > Marc > > -- > Pengutronix e.K. | Marc Kleine-Budde | > Industrial Linux Solutions | Phone: +49-231-2826-924 | > Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | > Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
