From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH v4 2/4] HID: steam: add serial number information. Date: Wed, 28 Feb 2018 22:17:50 +0200 Message-ID: References: <20180228184322.29636-1-rodrigorivascosta@gmail.com> <20180228184322.29636-3-rodrigorivascosta@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20180228184322.29636-3-rodrigorivascosta@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Rodrigo Rivas Costa Cc: Jiri Kosina , Benjamin Tissoires , "Pierre-Loup A. Griffais" , Cameron Gutman , =?UTF-8?Q?Cl=C3=A9ment_VUCHENER?= , Linux Kernel Mailing List , linux-input List-Id: linux-input@vger.kernel.org On Wed, Feb 28, 2018 at 8:43 PM, Rodrigo Rivas Costa 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 > #include > #include > +#include 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