From: Johan Hovold <johan@kernel.org> To: Macpaul Lin <macpaul.lin@mediatek.com> Cc: Johan Hovold <johan@kernel.org>, Oliver Neukum <oneukum@suse.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, linux-usb@vger.kernel.org, stable@vger.kernel.org, Mediatek WSD Upstream <wsd_upstream@mediatek.com> Subject: Re: [PATCH v3] cdc-acm: fix abnormal DATA RX issue for Mediatek Preloader. Date: Tue, 18 Dec 2018 11:54:19 +0100 [thread overview] Message-ID: <20181218105419.GL20658@localhost> (raw) In-Reply-To: <1545129680-3224-1-git-send-email-macpaul.lin@mediatek.com> On Tue, Dec 18, 2018 at 06:41:20PM +0800, Macpaul Lin wrote: > Mediatek Preloader is a proprietary embedded boot loader for loading > Little Kernel and Linux into device DRAM. > > This boot loader also handle firmware update. Mediatek Preloader will be > enumerated as a virtual COM port when the device is connected to Windows > or Linux OS via CDC-ACM class driver. When the USB enumeration has been > done, Mediatek Preloader will send out handshake command "READY" to PC > actively instead of waiting command from the download tool. > Since Linux 4.12, the commit "tty: reset termios state on device > registration" (93857edd9829e144acb6c7e72d593f6e01aead66) causes Mediatek > Preloader receiving some abnoraml command like "READYXX" as it sent. > This will be recognized as an incorrect response. The behavior change > also causes the download handshake fail. > > By disabling the ECHO termios flag could avoid this problem. However, it > cannot be done by user space configuration when download tool open > /dev/ttyACM0. This is because the device running Mediatek Preloader will > send handshake command "READY" immediately once the CDC-ACM driver is > ready. > > This patch wants to fix above problem by introducing "DISABLE_ECHO" > property in driver_info. When Mediatek Preloader is connected, the > CDC-ACM driver could disable ECHO flag in termios to avoid the problem. > > Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com> > --- > Changes for v2: > - Move quirks testing of DISABLE_ECHO flag into acm_tty_install(). > - Change quirks testing into bitwise comparison. > Changes for v3: > - Replace clear flag operation from driver->init_termios to tty->termios. > - Remove parenthesis of ECHO flag. Thanks for the update. Looks good, just some minor issues below. > drivers/usb/class/cdc-acm.c | 13 ++++++++++++- > drivers/usb/class/cdc-acm.h | 1 + > 2 files changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c > index 1b68fed..c1b88c3 100644 > --- a/drivers/usb/class/cdc-acm.c > +++ b/drivers/usb/class/cdc-acm.c > @@ -571,6 +571,7 @@ static void acm_softint(struct work_struct *work) > static int acm_tty_install(struct tty_driver *driver, struct tty_struct *tty) > { > struct acm *acm; > + unsigned long quirks; > int retval; > > acm = acm_get_by_minor(tty->index); > @@ -583,6 +584,13 @@ static int acm_tty_install(struct tty_driver *driver, struct tty_struct *tty) > > tty->driver_data = acm; > > + /* get normal quirks */ > + quirks = acm->quirks; I'd drop the quirks variable as you only need it once and acm->quirks is pretty short to begin with. > + > + /* handle active handshake triggered by device */ Please make this description more general; other devices may also end up needing to suppress initial echoing. > + if (quirks & DISABLE_ECHO) > + tty->termios.c_lflag &= ~ECHO; And finally, please move this just after installing the tty (i.e. before setting tty->driver data). > + > return 0; Thanks, Johan
WARNING: multiple messages have this Message-ID (diff)
From: Johan Hovold <johan@kernel.org> To: Macpaul Lin <macpaul.lin@mediatek.com> Cc: Johan Hovold <johan@kernel.org>, Oliver Neukum <oneukum@suse.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, linux-usb@vger.kernel.org, stable@vger.kernel.org, Mediatek WSD Upstream <wsd_upstream@mediatek.com> Subject: [v3] cdc-acm: fix abnormal DATA RX issue for Mediatek Preloader. Date: Tue, 18 Dec 2018 11:54:19 +0100 [thread overview] Message-ID: <20181218105419.GL20658@localhost> (raw) On Tue, Dec 18, 2018 at 06:41:20PM +0800, Macpaul Lin wrote: > Mediatek Preloader is a proprietary embedded boot loader for loading > Little Kernel and Linux into device DRAM. > > This boot loader also handle firmware update. Mediatek Preloader will be > enumerated as a virtual COM port when the device is connected to Windows > or Linux OS via CDC-ACM class driver. When the USB enumeration has been > done, Mediatek Preloader will send out handshake command "READY" to PC > actively instead of waiting command from the download tool. > Since Linux 4.12, the commit "tty: reset termios state on device > registration" (93857edd9829e144acb6c7e72d593f6e01aead66) causes Mediatek > Preloader receiving some abnoraml command like "READYXX" as it sent. > This will be recognized as an incorrect response. The behavior change > also causes the download handshake fail. > > By disabling the ECHO termios flag could avoid this problem. However, it > cannot be done by user space configuration when download tool open > /dev/ttyACM0. This is because the device running Mediatek Preloader will > send handshake command "READY" immediately once the CDC-ACM driver is > ready. > > This patch wants to fix above problem by introducing "DISABLE_ECHO" > property in driver_info. When Mediatek Preloader is connected, the > CDC-ACM driver could disable ECHO flag in termios to avoid the problem. > > Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com> > --- > Changes for v2: > - Move quirks testing of DISABLE_ECHO flag into acm_tty_install(). > - Change quirks testing into bitwise comparison. > Changes for v3: > - Replace clear flag operation from driver->init_termios to tty->termios. > - Remove parenthesis of ECHO flag. Thanks for the update. Looks good, just some minor issues below. > drivers/usb/class/cdc-acm.c | 13 ++++++++++++- > drivers/usb/class/cdc-acm.h | 1 + > 2 files changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c > index 1b68fed..c1b88c3 100644 > --- a/drivers/usb/class/cdc-acm.c > +++ b/drivers/usb/class/cdc-acm.c > @@ -571,6 +571,7 @@ static void acm_softint(struct work_struct *work) > static int acm_tty_install(struct tty_driver *driver, struct tty_struct *tty) > { > struct acm *acm; > + unsigned long quirks; > int retval; > > acm = acm_get_by_minor(tty->index); > @@ -583,6 +584,13 @@ static int acm_tty_install(struct tty_driver *driver, struct tty_struct *tty) > > tty->driver_data = acm; > > + /* get normal quirks */ > + quirks = acm->quirks; I'd drop the quirks variable as you only need it once and acm->quirks is pretty short to begin with. > + > + /* handle active handshake triggered by device */ Please make this description more general; other devices may also end up needing to suppress initial echoing. > + if (quirks & DISABLE_ECHO) > + tty->termios.c_lflag &= ~ECHO; And finally, please move this just after installing the tty (i.e. before setting tty->driver data). > + > return 0; Thanks, Johan
next prev parent reply other threads:[~2018-12-18 10:54 UTC|newest] Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-12-13 3:27 cdc-acm: fix abnormal DATA RX issue for Mediatek Preloader macpaul.lin 2018-12-18 5:00 ` [PATCH v2] " Macpaul Lin 2018-12-18 5:00 ` [v2] " macpaul.lin 2018-12-18 9:02 ` [PATCH v2] " Johan Hovold 2018-12-18 9:02 ` [v2] " Johan Hovold 2018-12-18 10:41 ` [PATCH v3] " Macpaul Lin 2018-12-18 10:41 ` [v3] " macpaul.lin 2018-12-18 10:54 ` Johan Hovold [this message] 2018-12-18 10:54 ` Johan Hovold 2018-12-18 11:38 ` [PATCH v4] " Macpaul Lin 2018-12-18 11:38 ` [v4] " macpaul.lin 2018-12-18 11:44 ` [PATCH v4] " Johan Hovold 2018-12-18 11:44 ` [v4] " Johan Hovold 2018-12-18 11:59 ` [PATCH v5] " Macpaul Lin 2018-12-18 11:59 ` [v5] " macpaul.lin 2018-12-18 12:38 ` [PATCH v5] " Johan Hovold 2018-12-18 12:38 ` [v5] " Johan Hovold 2018-12-18 13:37 ` [PATCH v5] " Oliver Neukum 2018-12-18 13:37 ` [v5] " Oliver Neukum 2018-12-18 14:26 ` [PATCH v5] " Macpaul Lin 2018-12-18 14:26 ` [v5] " macpaul.lin 2018-12-18 15:19 ` [PATCH v5] " Macpaul Lin 2018-12-18 15:19 ` [v5] " macpaul.lin 2018-12-18 16:42 ` [PATCH v5] " Lars Melin 2018-12-18 16:42 ` [v5] " Lars Melin 2018-12-18 17:48 ` [PATCH v5] " Macpaul Lin 2018-12-18 17:48 ` [v5] " macpaul.lin 2018-12-19 0:45 ` [PATCH v5] " Lars Melin 2018-12-19 0:45 ` [v5] " Lars Melin 2018-12-19 2:22 ` [PATCH v5] " Macpaul Lin 2018-12-19 2:22 ` [v5] " macpaul.lin 2018-12-19 3:16 ` [PATCH v5] " Macpaul Lin 2018-12-19 3:16 ` [v5] " macpaul.lin 2018-12-19 3:31 ` [PATCH v5] " Lars Melin 2018-12-19 3:31 ` [v5] " Lars Melin 2018-12-19 4:03 ` [PATCH v5] " Macpaul Lin 2018-12-19 4:03 ` [v5] " macpaul.lin 2018-12-19 8:56 ` [PATCH v5] " Oliver Neukum 2018-12-19 8:56 ` [v5] " Oliver Neukum 2018-12-20 15:19 ` [PATCH v5] " Greg Kroah-Hartman 2018-12-20 15:19 ` [v5] " Greg Kroah-Hartman 2018-12-18 15:37 ` [PATCH v6] " Macpaul Lin 2018-12-18 15:37 ` [v6] " macpaul.lin 2018-12-19 4:11 ` [PATCH v7] " Macpaul Lin 2018-12-19 4:11 ` [v7] " macpaul.lin 2018-12-19 9:00 ` [PATCH v7] " Johan Hovold 2018-12-19 9:00 ` [v7] " Johan Hovold 2018-12-20 15:28 ` [PATCH v7] " Oliver Neukum 2018-12-20 15:28 ` [v7] " Oliver Neukum
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