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[85.228.174.190]) by smtp.gmail.com with ESMTPSA id f1sm1495042lfm.184.2020.12.04.01.23.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Dec 2020 01:23:52 -0800 (PST) Received: from johan by xi.terra with local (Exim 4.93.0.4) (envelope-from ) id 1kl7KD-0005Lt-5H; Fri, 04 Dec 2020 10:24:25 +0100 Date: Fri, 4 Dec 2020 10:24:25 +0100 From: Johan Hovold To: Himadri Pandya Cc: johan@kernel.org, gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: Re: [PATCH 03/15] usb: serial: ch314: use usb_control_msg_recv() and usb_control_msg_send() Message-ID: References: <20201104064703.15123-1-himadrispandya@gmail.com> <20201104064703.15123-4-himadrispandya@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201104064703.15123-4-himadrispandya@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Wed, Nov 04, 2020 at 12:16:51PM +0530, Himadri Pandya wrote: > The new usb_control_msg_recv() and usb_control_msg_send() nicely wraps > usb_control_msg() with proper error check. Hence use the wrappers > instead of calling usb_control_msg() directly. > > Signed-off-by: Himadri Pandya > --- > drivers/usb/serial/ch341.c | 45 ++++++++++++-------------------------- > 1 file changed, 14 insertions(+), 31 deletions(-) > > diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c > index a2e2f56c88cd..58c5d3ce4f75 100644 > --- a/drivers/usb/serial/ch341.c > +++ b/drivers/usb/serial/ch341.c > @@ -111,10 +111,10 @@ static int ch341_control_out(struct usb_device *dev, u8 request, > dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__, > request, value, index); > > - r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request, > - USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT, > - value, index, NULL, 0, DEFAULT_TIMEOUT); > - if (r < 0) > + r = usb_control_msg_send(dev, 0, request, USB_TYPE_VENDOR | > + USB_RECIP_DEVICE | USB_DIR_OUT, value, index, > + NULL, 0, DEFAULT_TIMEOUT, GFP_KERNEL); > + if (r) > dev_err(&dev->dev, "failed to send control message: %d\n", r); > > return r; > @@ -129,23 +129,14 @@ static int ch341_control_in(struct usb_device *dev, > dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__, > request, value, index, bufsize); > > - r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request, > - USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN, > - value, index, buf, bufsize, DEFAULT_TIMEOUT); > - if (r < (int)bufsize) { > - if (r >= 0) { > - dev_err(&dev->dev, > - "short control message received (%d < %u)\n", > - r, bufsize); > - r = -EIO; > - } > - > + r = usb_control_msg_recv(dev, 0, request, USB_TYPE_VENDOR | > + USB_RECIP_DEVICE | USB_DIR_IN, value, index, > + buf, bufsize, DEFAULT_TIMEOUT, GFP_KERNEL); > + if (r) > dev_err(&dev->dev, "failed to receive control message: %d\n", > r); > - return r; > - } > > - return 0; > + return r; > } The callers of these functions are allocating temporary transfers buffer for each request so this is a case where the new helpers may be of worth if you fix up the callers as well (otherwise, you're adding redundant memdup + memcpy for each call here). > > #define CH341_CLKRATE 48000000 > @@ -343,22 +334,18 @@ static int ch341_detect_quirks(struct usb_serial_port *port) > struct usb_device *udev = port->serial->dev; > const unsigned int size = 2; > unsigned long quirks = 0; > - char *buffer; > + u8 buffer[2]; > int r; > > - buffer = kmalloc(size, GFP_KERNEL); > - if (!buffer) > - return -ENOMEM; > - > /* > * A subset of CH34x devices does not support all features. The > * prescaler is limited and there is no support for sending a RS232 > * break condition. A read failure when trying to set up the latter is > * used to detect these devices. > */ > - r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG, > - USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN, > - CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT); > + r = usb_control_msg_recv(udev, 0, CH341_REQ_READ_REG, USB_TYPE_VENDOR | > + USB_RECIP_DEVICE | USB_DIR_IN, CH341_REG_BREAK, > + 0, &buffer, size, DEFAULT_TIMEOUT, GFP_KERNEL); > if (r == -EPIPE) { > dev_info(&port->dev, "break control not supported, using simulated break\n"); > quirks = CH341_QUIRK_LIMITED_PRESCALER | CH341_QUIRK_SIMULATE_BREAK; > @@ -366,17 +353,13 @@ static int ch341_detect_quirks(struct usb_serial_port *port) > goto out; > } > > - if (r != size) { > - if (r >= 0) > - r = -EIO; > + if (r) { > dev_err(&port->dev, "failed to read break control: %d\n", r); > goto out; > } > > r = 0; > out: > - kfree(buffer); > - > if (quirks) { > dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks); > priv->quirks |= quirks; This is a good example of when to use the helpers. But it seems you should remove the "r = 0" and "out" label as well, right? Johan