Messages in this thread | | | From | Andy Shevchenko <> | Date | Wed, 28 Feb 2018 22:17:50 +0200 | Subject | Re: [PATCH v4 2/4] HID: steam: add serial number information. |
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On Wed, Feb 28, 2018 at 8:43 PM, Rodrigo Rivas Costa <rodrigorivascosta@gmail.com> wrote: > This device has a feature report to send and receive commands. > Use it to get the serial number and set the device's uniq value.
> #include <linux/module.h> > #include <linux/workqueue.h> > #include <linux/rcupdate.h>
> +#include <linux/delay.h>
Better to keep it somehow sorted (yes, I see it's not originally, but better to squeeze new header to the most ordered part).
> @@ -41,8 +42,99 @@ struct steam_device { > unsigned long quirks; > struct work_struct work_connect; > bool connected;
> + char serial_no[11];
11 is a magic.
> }; > > +static int steam_recv_report(struct steam_device *steam, > + u8 *data, int size) > +{ > + struct hid_report *r; > + u8 *buf; > + int ret; > + > + r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0]; > + if (hid_report_len(r) < 64) > + return -EINVAL;
+ empty line.
> + buf = hid_alloc_report_buf(r, GFP_KERNEL); > + if (!buf) > + return -ENOMEM; > + > + /* > + * The report ID is always 0, so strip the first byte from the output. > + * hid_report_len() is not counting the report ID, so +1 to the length > + * or else we get a EOVERFLOW. We are safe from a buffer overflow > + * because hid_alloc_report_buf() allocates +7 bytes. > + */ > + ret = hid_hw_raw_request(steam->hdev, 0x00, > + buf, hid_report_len(r) + 1, > + HID_FEATURE_REPORT, HID_REQ_GET_REPORT); > + if (ret > 0) > + memcpy(data, buf + 1, min(size, ret - 1)); > + kfree(buf); > + return ret; > +} > + > +static int steam_send_report(struct steam_device *steam, > + u8 *cmd, int size) > +{ > + struct hid_report *r; > + u8 *buf; > + int retry; > + int ret; > + > + r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0]; > + if (hid_report_len(r) < 64) > + return -EINVAL;
+empty line.
> + buf = hid_alloc_report_buf(r, GFP_KERNEL); > + if (!buf) > + return -ENOMEM; > + > + /* The report ID is always 0 */ > + memcpy(buf + 1, cmd, size); > + > + /* > + * Sometimes the wireless controller fails with EPIPE > + * when sending a feature report. > + * Doing a HID_REQ_GET_REPORT and waiting for a while > + * seems to fix that. > + */
> + for (retry = 0; retry < 10; ++retry) { > + ret = hid_hw_raw_request(steam->hdev, 0, > + buf, size + 1, > + HID_FEATURE_REPORT, HID_REQ_SET_REPORT); > + if (ret != -EPIPE) > + break; > + steam_recv_report(steam, NULL, 0); > + msleep(50); > + }
Personally I consider do{}while in case of "timeout loops" much easier to parse.
unsigned int retry = 10; ...
do { ... } while (--retry);
> + kfree(buf); > + if (ret < 0) > + hid_err(steam->hdev, "%s: error %d (%*ph)\n", __func__, > + ret, size, cmd); > + return ret; > +} > + > +static int steam_get_serial(struct steam_device *steam) > +{ > + /* > + * Send: 0xae 0x15 0x01 > + * Recv: 0xae 0x15 0x01 serialnumber (10 chars) > + */ > + int ret; > + u8 cmd[] = {0xae, 0x15, 0x01};
> + u8 reply[14]; > + > + ret = steam_send_report(steam, cmd, sizeof(cmd)); > + if (ret < 0) > + return ret; > + ret = steam_recv_report(steam, reply, sizeof(reply)); > + if (ret < 0) > + return ret;
> + reply[13] = 0; > + strcpy(steam->serial_no, reply + 3);
strlcpy()
> + return 0; > +}
-- With Best Regards, Andy Shevchenko
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