From 95e9e600fe1cb8270f7dbbd697f74b49508f54b0 Mon Sep 17 00:00:00 2001
From: Torleiv Sundre <torleiv@huddly.com>
Date: Thu, 14 Nov 2024 20:37:52 +0100
Subject: [PATCH] lsusb: improve usb2 device capability descriptor

Fix the following issues with the usb2 device capability descriptor
dump:

Currently, the BESL values claim to be in microseconds, but are actually
the raw, unshifted values from the descriptor. Use a lookup table for
the BESL values, based on Table X-X1 from "Errata for USB 2.0 ECN: Link
Power Management (LPM) - 7/2007" to display the actual microsecond
values.

Currently, the BESL values are displayed at the same indentation level
as bmAttributes, even though they are fields in bmAttributes. Adjust
indentation to align all fields of bmAttributes.

Change "BESL value" to "Baseline BESL value", to reflect the actual
names of the field.

Remove two unnecessary line breaks.

Before change:
  USB 2.0 Extension Device Capability:
    bLength                 7
    bDescriptorType        16
    bDevCapabilityType      2
    bmAttributes   0x0000f41e
      BESL Link Power Management (LPM) Supported
    BESL value     1024 us
    Deep BESL value    61440 us

After change:
  USB 2.0 Extension Device Capability:
    bLength                 7
    bDescriptorType        16
    bDevCapabilityType      2
    bmAttributes   0x0000f41e
      BESL Link Power Management (LPM) Supported
      Baseline BESL value    400 us
      Deep BESL value      10000 us
---
 lsusb.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/lsusb.c b/lsusb.c
index 0b74182..a987261 100644
--- a/lsusb.c
+++ b/lsusb.c
@@ -3217,7 +3217,10 @@ dump_device_status(libusb_device_handle *fd, int otg, int super_speed)
 
 static void dump_usb2_device_capability_desc(unsigned char *buf, bool lpm_required)
 {
+	static const uint16_t besl_us[16] = { 125,  150,  200,	300,  400,  500,  1000, 2000,
+					      3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000 };
 	unsigned int wide;
+	unsigned int besl;
 
 	wide = buf[3] + (buf[4] << 8) +
 		(buf[5] << 16) + (buf[6] << 24);
@@ -3232,16 +3235,17 @@ static void dump_usb2_device_capability_desc(unsigned char *buf, bool lpm_requir
 	else if (!lpm_required && !(wide & 0x02))
 		printf("      Link Power Management (LPM) not supported\n");
 	else if (!(wide & 0x04))
-		printf("      HIRD Link Power Management (LPM)"
-				" Supported\n");
+		printf("      HIRD Link Power Management (LPM) Supported\n");
 	else {
-		printf("      BESL Link Power Management (LPM)"
-				" Supported\n");
-		if (wide & 0x08)
-			printf("    BESL value    %5u us \n", wide & 0xf00);
-		if (wide & 0x10)
-			printf("    Deep BESL value    %5u us \n",
-					wide & 0xf000);
+		printf("      BESL Link Power Management (LPM) Supported\n");
+		if (wide & 0x08) {
+			besl = (wide & 0xf00) >> 8;
+			printf("      Baseline BESL value  %5hu us \n", besl_us[besl]);
+		}
+		if (wide & 0x10) {
+			besl = (wide & 0xf000) >> 12;
+			printf("      Deep BESL value      %5hu us \n", besl_us[besl]);
+		}
 	}
 }