Re: [PATCHv2] i2c: i2c-tiny-usb: fix buffer not being DMA capable

Sebastian Reichel
2017-05-20T16:10:11Z

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Hi,

ping?

This fixes a regression making the driver effectively useless.

-- Sebastian

On Fri, May 05, 2017 at 11:06:50AM +0200, Sebastian Reichel wrote:
> Since v4.9 i2c-tiny-usb generates the below call trace
> and longer works, since it can't communicate with the
> USB device. The reason is, that since v4.9 the USB
> stack checks, that the buffer it should transfer is DMA
> capable. This was a requirement since v2.2 days, but it
> usually worked nevertheless.
>
> [ 17.504959] ------------[ cut here ]------------
> [ 17.505488] WARNING: CPU: 0 PID: 93 at drivers/usb/core/hcd.c:1587 usb_hcd_map_urb_for_dma+0x37c/0x570
> [ 17.506545] transfer buffer not dma capable
> [ 17.507022] Modules linked in:
> [ 17.507370] CPU: 0 PID: 93 Comm: i2cdetect Not tainted 4.11.0-rc8+ #10
> [ 17.508103] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> [ 17.509039] Call Trace:
> [ 17.509320] ? dump_stack+0x5c/0x78
> [ 17.509714] ? __warn+0xbe/0xe0
> [ 17.510073] ? warn_slowpath_fmt+0x5a/0x80
> [ 17.510532] ? nommu_map_sg+0xb0/0xb0
> [ 17.510949] ? usb_hcd_map_urb_for_dma+0x37c/0x570
> [ 17.511482] ? usb_hcd_submit_urb+0x336/0xab0
> [ 17.511976] ? wait_for_completion_timeout+0x12f/0x1a0
> [ 17.512549] ? wait_for_completion_timeout+0x65/0x1a0
> [ 17.513125] ? usb_start_wait_urb+0x65/0x160
> [ 17.513604] ? usb_control_msg+0xdc/0x130
> [ 17.514061] ? usb_xfer+0xa4/0x2a0
> [ 17.514445] ? __i2c_transfer+0x108/0x3c0
> [ 17.514899] ? i2c_transfer+0x57/0xb0
> [ 17.515310] ? i2c_smbus_xfer_emulated+0x12f/0x590
> [ 17.515851] ? _raw_spin_unlock_irqrestore+0x11/0x20
> [ 17.516408] ? i2c_smbus_xfer+0x125/0x330
> [ 17.516876] ? i2c_smbus_xfer+0x125/0x330
> [ 17.517329] ? i2cdev_ioctl_smbus+0x1c1/0x2b0
> [ 17.517824] ? i2cdev_ioctl+0x75/0x1c0
> [ 17.518248] ? do_vfs_ioctl+0x9f/0x600
> [ 17.518671] ? vfs_write+0x144/0x190
> [ 17.519078] ? SyS_ioctl+0x74/0x80
> [ 17.519463] ? entry_SYSCALL_64_fastpath+0x1e/0xad
> [ 17.519959] ---[ end trace d047c04982f5ac50 ]---
>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> ---
> Changes since PATCHv1:
> - update patch description, drop # v4.9+ from stable cc
> - add missing checks for kmemdup/kmalloc
> ---
> drivers/i2c/busses/i2c-tiny-usb.c | 25 +++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c
> index 0ed77eeff31e..a2e3dd715380 100644
> --- a/drivers/i2c/busses/i2c-tiny-usb.c
> +++ b/drivers/i2c/busses/i2c-tiny-usb.c
> @@ -178,22 +178,39 @@ static int usb_read(struct i2c_adapter *adapter, int cmd,
> int value, int index, void *data, int len)
> {
> struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
> + void *dmadata = kmalloc(len, GFP_KERNEL);
> + int ret;
> +
> + if (!dmadata)
> + return -ENOMEM;
>
> /* do control transfer */
> - return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
> + ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
> cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
> - USB_DIR_IN, value, index, data, len, 2000);
> + USB_DIR_IN, value, index, dmadata, len, 2000);
> +
> + memcpy(data, dmadata, len);
> + kfree(dmadata);
> + return ret;
> }
>
> static int usb_write(struct i2c_adapter *adapter, int cmd,
> int value, int index, void *data, int len)
> {
> struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
> + void *dmadata = kmemdup(data, len, GFP_KERNEL);
> + int ret;
> +
> + if (!dmadata)
> + return -ENOMEM;
>
> /* do control transfer */
> - return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
> + ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
> cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
> - value, index, data, len, 2000);
> + value, index, dmadata, len, 2000);
> +
> + kfree(dmadata);
> + return ret;
> }
>
> static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
> --
> 2.11.0