diff mbox series

[v1,1/3] usb: typec: ucsi: Limit read size on v1.2

Message ID 20240123143026.v1.1.Iacf5570a66b82b73ef03daa6557e2fc0db10266a@changeid (mailing list archive)
State Superseded
Headers show
Series usb: typec: ucsi: Adding support for UCSI 3.0 | expand

Commit Message

Abhishek Pandit-Subedi Jan. 23, 2024, 10:30 p.m. UTC 
From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>

Between UCSI 1.2 and UCSI 2.0, the size of the MESSAGE_IN region was
increased from 16 to 256. In order to avoid overflowing reads for older
systems, add a mechanism to use the read UCSI version to truncate read
sizes on UCSI v1.2.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
---
Tested on 6.6 kernel. Dmesg output from this change:
[  105.058162] ucsi_um_test ucsi_um_test_device.0: Registered UCSI
interface with version 3.0.0


 drivers/usb/typec/ucsi/ucsi.c | 26 ++++++++++++++++++++++++--
 drivers/usb/typec/ucsi/ucsi.h | 11 +++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

Comments

Prashant Malani Jan. 24, 2024, 8:12 a.m. UTC | #1 
Hi Abhishek,

On Tue, Jan 23, 2024 at 2:30 PM Abhishek Pandit-Subedi
<abhishekpandit@google.com> wrote:
>
> From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>
> Between UCSI 1.2 and UCSI 2.0, the size of the MESSAGE_IN region was
> increased from 16 to 256. In order to avoid overflowing reads for older
> systems, add a mechanism to use the read UCSI version to truncate read
> sizes on UCSI v1.2.
>
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
I have one nit (mentioned in side-band but reproducing here for consistency),
but will defer to the maintainer on that.

The above notwithstanding, FWIW:
Reviewed-by: Prashant Malani<pmalani@chromium.org>

> @@ -1556,6 +1569,15 @@ int ucsi_register(struct ucsi *ucsi)
>         if (!ucsi->version)
>                 return -ENODEV;
>
> +       /*
> +        * Version format is JJ.M.N (JJ = Major version, M = Minor version,
> +        * N = sub-minor version).
> +        */
> +       dev_info(ucsi->dev, "Registered UCSI interface with version %x.%x.%x",
> +                UCSI_BCD_GET_MAJOR(ucsi->version),
> +                UCSI_BCD_GET_MINOR(ucsi->version),
> +                UCSI_BCD_GET_SUBMINOR(ucsi->version));

nit: I think this doesn't need to be dev_info() and can be just
dev_dbg(), but will
defer to the maintainer.

Thanks,

-Prashant
Heikki Krogerus Jan. 24, 2024, 1:51 p.m. UTC | #2 
On Wed, Jan 24, 2024 at 12:12:26AM -0800, Prashant Malani wrote:
> Hi Abhishek,
> 
> On Tue, Jan 23, 2024 at 2:30 PM Abhishek Pandit-Subedi
> <abhishekpandit@google.com> wrote:
> >
> > From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> >
> > Between UCSI 1.2 and UCSI 2.0, the size of the MESSAGE_IN region was
> > increased from 16 to 256. In order to avoid overflowing reads for older
> > systems, add a mechanism to use the read UCSI version to truncate read
> > sizes on UCSI v1.2.
> >
> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> I have one nit (mentioned in side-band but reproducing here for consistency),
> but will defer to the maintainer on that.
> 
> The above notwithstanding, FWIW:
> Reviewed-by: Prashant Malani<pmalani@chromium.org>
> 
> > @@ -1556,6 +1569,15 @@ int ucsi_register(struct ucsi *ucsi)
> >         if (!ucsi->version)
> >                 return -ENODEV;
> >
> > +       /*
> > +        * Version format is JJ.M.N (JJ = Major version, M = Minor version,
> > +        * N = sub-minor version).
> > +        */
> > +       dev_info(ucsi->dev, "Registered UCSI interface with version %x.%x.%x",
> > +                UCSI_BCD_GET_MAJOR(ucsi->version),
> > +                UCSI_BCD_GET_MINOR(ucsi->version),
> > +                UCSI_BCD_GET_SUBMINOR(ucsi->version));
> 
> nit: I think this doesn't need to be dev_info() and can be just
> dev_dbg(), but will
> defer to the maintainer.

I think that's okay.

Reviewewd-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Greg Kroah-Hartman Jan. 24, 2024, 2:17 p.m. UTC | #3 
On Wed, Jan 24, 2024 at 03:51:58PM +0200, Heikki Krogerus wrote:
> On Wed, Jan 24, 2024 at 12:12:26AM -0800, Prashant Malani wrote:
> > Hi Abhishek,
> > 
> > On Tue, Jan 23, 2024 at 2:30 PM Abhishek Pandit-Subedi
> > <abhishekpandit@google.com> wrote:
> > >
> > > From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > >
> > > Between UCSI 1.2 and UCSI 2.0, the size of the MESSAGE_IN region was
> > > increased from 16 to 256. In order to avoid overflowing reads for older
> > > systems, add a mechanism to use the read UCSI version to truncate read
> > > sizes on UCSI v1.2.
> > >
> > > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > I have one nit (mentioned in side-band but reproducing here for consistency),
> > but will defer to the maintainer on that.
> > 
> > The above notwithstanding, FWIW:
> > Reviewed-by: Prashant Malani<pmalani@chromium.org>
> > 
> > > @@ -1556,6 +1569,15 @@ int ucsi_register(struct ucsi *ucsi)
> > >         if (!ucsi->version)
> > >                 return -ENODEV;
> > >
> > > +       /*
> > > +        * Version format is JJ.M.N (JJ = Major version, M = Minor version,
> > > +        * N = sub-minor version).
> > > +        */
> > > +       dev_info(ucsi->dev, "Registered UCSI interface with version %x.%x.%x",
> > > +                UCSI_BCD_GET_MAJOR(ucsi->version),
> > > +                UCSI_BCD_GET_MINOR(ucsi->version),
> > > +                UCSI_BCD_GET_SUBMINOR(ucsi->version));
> > 
> > nit: I think this doesn't need to be dev_info() and can be just
> > dev_dbg(), but will
> > defer to the maintainer.
> 
> I think that's okay.
> 
> Reviewewd-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

No, when drivers are working properly they are quiet, this needs to be
dev_dbg().

thanks,

greg k-h
Abhishek Pandit-Subedi Jan. 24, 2024, 6:59 p.m. UTC | #4 
Ack. Will make dev_dbg on the next iteration.

This seems like a good addition to the style guide too:
https://www.kernel.org/doc/html/v6.7/process/coding-style.html#printing-kernel-messages.
"When drivers are working properly, they are quiet. Prefer to use
DEBUG messages unless something is wrong."

What do you think Greg?

On Wed, Jan 24, 2024 at 6:17 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Jan 24, 2024 at 03:51:58PM +0200, Heikki Krogerus wrote:
> > On Wed, Jan 24, 2024 at 12:12:26AM -0800, Prashant Malani wrote:
> > > Hi Abhishek,
> > >
> > > On Tue, Jan 23, 2024 at 2:30 PM Abhishek Pandit-Subedi
> > > <abhishekpandit@google.com> wrote:
> > > >
> > > > From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > > >
> > > > Between UCSI 1.2 and UCSI 2.0, the size of the MESSAGE_IN region was
> > > > increased from 16 to 256. In order to avoid overflowing reads for older
> > > > systems, add a mechanism to use the read UCSI version to truncate read
> > > > sizes on UCSI v1.2.
> > > >
> > > > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > > I have one nit (mentioned in side-band but reproducing here for consistency),
> > > but will defer to the maintainer on that.
> > >
> > > The above notwithstanding, FWIW:
> > > Reviewed-by: Prashant Malani<pmalani@chromium.org>
> > >
> > > > @@ -1556,6 +1569,15 @@ int ucsi_register(struct ucsi *ucsi)
> > > >         if (!ucsi->version)
> > > >                 return -ENODEV;
> > > >
> > > > +       /*
> > > > +        * Version format is JJ.M.N (JJ = Major version, M = Minor version,
> > > > +        * N = sub-minor version).
> > > > +        */
> > > > +       dev_info(ucsi->dev, "Registered UCSI interface with version %x.%x.%x",
> > > > +                UCSI_BCD_GET_MAJOR(ucsi->version),
> > > > +                UCSI_BCD_GET_MINOR(ucsi->version),
> > > > +                UCSI_BCD_GET_SUBMINOR(ucsi->version));
> > >
> > > nit: I think this doesn't need to be dev_info() and can be just
> > > dev_dbg(), but will
> > > defer to the maintainer.
> >
> > I think that's okay.
> >
> > Reviewewd-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>
> No, when drivers are working properly they are quiet, this needs to be
> dev_dbg().
>
> thanks,
>
> greg k-h
>
Greg Kroah-Hartman Jan. 25, 2024, 11:16 p.m. UTC | #5 
On Wed, Jan 24, 2024 at 10:59:28AM -0800, Abhishek Pandit-Subedi wrote:
> Ack. Will make dev_dbg on the next iteration.
> 
> This seems like a good addition to the style guide too:
> https://www.kernel.org/doc/html/v6.7/process/coding-style.html#printing-kernel-messages.
> "When drivers are working properly, they are quiet. Prefer to use
> DEBUG messages unless something is wrong."
> 
> What do you think Greg?

I think you need to stop top-posting :)

But yes, that would be nice, hopefully people actually notice it there.
Would you have read this and seen it?

thanks,

greg k-h
Abhishek Pandit-Subedi Jan. 25, 2024, 11:37 p.m. UTC | #6 
On Thu, Jan 25, 2024 at 3:16 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Jan 24, 2024 at 10:59:28AM -0800, Abhishek Pandit-Subedi wrote:
> > Ack. Will make dev_dbg on the next iteration.
> >
> > This seems like a good addition to the style guide too:
> > https://www.kernel.org/doc/html/v6.7/process/coding-style.html#printing-kernel-messages.
> > "When drivers are working properly, they are quiet. Prefer to use
> > DEBUG messages unless something is wrong."
> >
> > What do you think Greg?
>
> I think you need to stop top-posting :)
>
> But yes, that would be nice, hopefully people actually notice it there.
> Would you have read this and seen it?
>
> thanks,
>
> greg k-h

I blame gmail web-interface for the top-posting :)

Prashant also mentioned the dev_info when we were reviewing this so I
did a quick search for "kernel coding style" (to see if there was
guidance) before sending this up so I would definitely have noticed it
there.
In Bluetooth (where I've previously contributed), dev_info is used for
printing version info (example:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/bluetooth/btintel.c?h=v6.8-rc1#n337)
and it's very useful for debugging so I assumed it was acceptable.

The added benefit of this guidance being in the coding style guide is
it's a quick change to checkpatch.pl to add a warning for this (and
point to the coding style as the source). I'm fairly sure Chromium
actually has a lint that warns whenever you use LOG_INFO(...) for
similar reasons (too many INFO messages that should be DEBUG).

I will send up a patch with the change soon (both to coding style and
checkpatch.pl).

Thanks,
Abhishek
diff mbox series

Patch

diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
index 5392ec698959..4edf785d203b 100644
--- a/drivers/usb/typec/ucsi/ucsi.c
+++ b/drivers/usb/typec/ucsi/ucsi.c
@@ -36,6 +36,19 @@ 
  */
 #define UCSI_SWAP_TIMEOUT_MS	5000
 
+static int ucsi_read_message_in(struct ucsi *ucsi, void *buf,
+					  size_t buf_size)
+{
+	/*
+	 * Below UCSI 2.0, MESSAGE_IN was limited to 16 bytes. Truncate the
+	 * reads here.
+	 */
+	if (ucsi->version <= UCSI_VERSION_1_2)
+		buf_size = min_t(size_t, 16, buf_size);
+
+	return ucsi->ops->read(ucsi, UCSI_MESSAGE_IN, buf, buf_size);
+}
+
 static int ucsi_acknowledge_command(struct ucsi *ucsi)
 {
 	u64 ctrl;
@@ -72,7 +85,7 @@  static int ucsi_read_error(struct ucsi *ucsi)
 	if (ret < 0)
 		return ret;
 
-	ret = ucsi->ops->read(ucsi, UCSI_MESSAGE_IN, &error, sizeof(error));
+	ret = ucsi_read_message_in(ucsi, &error, sizeof(error));
 	if (ret)
 		return ret;
 
@@ -170,7 +183,7 @@  int ucsi_send_command(struct ucsi *ucsi, u64 command,
 	length = ret;
 
 	if (data) {
-		ret = ucsi->ops->read(ucsi, UCSI_MESSAGE_IN, data, size);
+		ret = ucsi_read_message_in(ucsi, data, size);
 		if (ret)
 			goto out;
 	}
@@ -1556,6 +1569,15 @@  int ucsi_register(struct ucsi *ucsi)
 	if (!ucsi->version)
 		return -ENODEV;
 
+	/*
+	 * Version format is JJ.M.N (JJ = Major version, M = Minor version,
+	 * N = sub-minor version).
+	 */
+	dev_info(ucsi->dev, "Registered UCSI interface with version %x.%x.%x",
+		 UCSI_BCD_GET_MAJOR(ucsi->version),
+		 UCSI_BCD_GET_MINOR(ucsi->version),
+		 UCSI_BCD_GET_SUBMINOR(ucsi->version));
+
 	queue_delayed_work(system_long_wq, &ucsi->work, 0);
 
 	ucsi_debugfs_register(ucsi);
diff --git a/drivers/usb/typec/ucsi/ucsi.h b/drivers/usb/typec/ucsi/ucsi.h
index 6478016d5cb8..bec920fa6b8a 100644
--- a/drivers/usb/typec/ucsi/ucsi.h
+++ b/drivers/usb/typec/ucsi/ucsi.h
@@ -23,6 +23,17 @@  struct dentry;
 #define UCSI_CONTROL			8
 #define UCSI_MESSAGE_IN			16
 #define UCSI_MESSAGE_OUT		32
+#define UCSIv2_MESSAGE_OUT		272
+
+/* UCSI versions */
+#define UCSI_VERSION_1_2	0x0120
+#define UCSI_VERSION_2_0	0x0200
+#define UCSI_VERSION_2_1	0x0210
+#define UCSI_VERSION_3_0	0x0300
+
+#define UCSI_BCD_GET_MAJOR(_v_)		(((_v_) >> 8) & 0xFF)
+#define UCSI_BCD_GET_MINOR(_v_)		(((_v_) >> 4) & 0x0F)
+#define UCSI_BCD_GET_SUBMINOR(_v_)	((_v_) & 0x0F)
 
 /* Command Status and Connector Change Indication (CCI) bits */
 #define UCSI_CCI_CONNECTOR(_c_)		(((_c_) & GENMASK(7, 1)) >> 1)