Eric Lee / smarc-uboot

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Commit c008faa77358bb5b313696dd1d5bb8afa03a6ca2

Authored by Bin Meng
Committed by Marek Vasut
1 parent 1897d60130
Exists in smarc_8mq_lf_v2020.04 and in 17 other branches 8qm-imx_v2020.04_5.4.70_2.3.0, emb_lf_v2022.04, pitx_8mp_lf_v2020.04, smarc-8m-android-10.0.0_2.6.0, smarc-8m-android-11.0.0_2.0.0, smarc-8mp-android-11.0.0_2.0.0, smarc-imx6_v2018.03_4.14.98_2.0.0_ga, smarc-imx7_v2018.03_4.14.98_2.0.0_ga, smarc-imx_v2018.03_4.14.78_1.0.0_ga, smarc_8m-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8m-imx_v2019.04_4.19.35_1.1.0, smarc_8m_00d0-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2018.03_4.14.98_2.0.0_ga, smarc_8mm-imx_v2019.04_4.19.35_1.1.0, smarc_8mm-imx_v2020.04_5.4.24_2.1.0, smarc_8mp_lf_v2020.04, smarc_8mq-imx_v2020.04_5.4.24_2.1.0

usb: Only get 64 bytes device descriptor for full speed devices 

Full speed device endpoint 0 can have 8/16/32/64 bMaxPacketSize0.
Other speed devices report fixed value per USB spec. So it only
makes sense if we send a get device descriptor with 64 bytes to
full speed devices.

While we are here, update the comment block to be within 80 cols.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

Showing 1 changed file with 15 additions and 14 deletions Side-by-side Diff

... ... @@ -970,23 +970,24 @@
970 970 dev->epmaxpacketin[0] = dev->descriptor.bMaxPacketSize0;
971 971 dev->epmaxpacketout[0] = dev->descriptor.bMaxPacketSize0;
972 972  
973   - if (do_read) {
  973 + if (do_read && dev->speed == USB_SPEED_FULL) {
974 974 int err;
975 975  
976 976 /*
977   - * Validate we've received only at least 8 bytes, not that we've
978   - * received the entire descriptor. The reasoning is:
979   - * - The code only uses fields in the first 8 bytes, so that's all we
980   - * need to have fetched at this stage.
981   - * - The smallest maxpacket size is 8 bytes. Before we know the actual
982   - * maxpacket the device uses, the USB controller may only accept a
983   - * single packet. Consequently we are only guaranteed to receive 1
984   - * packet (at least 8 bytes) even in a non-error case.
  977 + * Validate we've received only at least 8 bytes, not that
  978 + * we've received the entire descriptor. The reasoning is:
  979 + * - The code only uses fields in the first 8 bytes, so
  980 + * that's all we need to have fetched at this stage.
  981 + * - The smallest maxpacket size is 8 bytes. Before we know
  982 + * the actual maxpacket the device uses, the USB controller
  983 + * may only accept a single packet. Consequently we are only
  984 + * guaranteed to receive 1 packet (at least 8 bytes) even in
  985 + * a non-error case.
985 986 *
986   - * At least the DWC2 controller needs to be programmed with the number
987   - * of packets in addition to the number of bytes. A request for 64
988   - * bytes of data with the maxpacket guessed as 64 (above) yields a
989   - * request for 1 packet.
  987 + * At least the DWC2 controller needs to be programmed with
  988 + * the number of packets in addition to the number of bytes.
  989 + * A request for 64 bytes of data with the maxpacket guessed
  990 + * as 64 (above) yields a request for 1 packet.
990 991 */
991 992 err = get_descriptor_len(dev, 64, 8);
992 993 if (err)
... ... @@ -1009,7 +1010,7 @@
1009 1010 dev->maxpacketsize = PACKET_SIZE_64;
1010 1011 break;
1011 1012 default:
1012   - printf("usb_new_device: invalid max packet size\n");
  1013 + printf("%s: invalid max packet size\n", __func__);
1013 1014 return -EIO;
1014 1015 }
1015 1016