examples: document and work around the i.MX RT and LPC55 USB erratafix-ci-hs

ERR050101: while an isochronous IN endpoint is active, an IN token addressed to
that same endpoint number on ANOTHER device sharing the host can silently
unprime one of this device's OUT endpoints - control, bulk, interrupt or
isochronous alike. NXP states it cannot be detected by software and raises no
interrupt, so the endpoint simply stops answering and the transfer never
completes.

The workaround is a uniqueness requirement rather than a particular number: the
isochronous IN endpoint must not share its number with any IN endpoint in use on
the bus. One family-wide constant therefore defeats it, since two affected
boards on the same hub then pick the same number and each becomes the other's
aggressor. CFG_TUSB_MIMXRT1XXX_ERRATA_ERR050101 is set only for the parts whose
errata list it - RT1015, RT1020, RT1024 and RT1050, where it is marked no fix
scheduled, plus RT1060 and RT1064 rev A - so RT1010 and the RT11xx family keep
the ordinary number and cannot collide with an affected board beside them.
Several affected boards on one hub can still be given distinct numbers with
-DEPNUM_ISO_IN.

The guard covers every example that has an isochronous IN endpoint: audio_test,
audio_4_channel_mic, uac2_headset, cdc_uac2, usbtest, video_capture and
video_capture_2ch. The video examples move the endpoint only when streaming
isochronously, since the bulk configuration is unaffected, and video_capture_2ch
takes two numbers because it has two streams.

The macro name follows CFG_TUSB_RP2_ERRATA_E2/E4/E15 already in tree, and its
is fixed, and which cannot be told apart at compile time - a way to define it to
0.

device_issues.rst records ERR050101 against every affected part with a link to
each errata sheet, and adds the LPC55S2x USB.3 speed-detection and USB.5
isochronous IN entries, neither of which TinyUSB works around. The branch's
design notes are included under docs/superpowers.

Verified: 340 wedge-free runs on mimxrt1064_evk, which previously wedged within
hours, and the macro resolving to endpoint 0x87 on mimxrt1064_evk against 0x83
on mimxrt1010_evk and stm32f407disco.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/common/tusb_mcu.h b/src/common/tusb_mcu.h
index 93b4a2ee9..af43dfb12 100644
--- a/src/common/tusb_mcu.h
+++ b/src/common/tusb_mcu.h
@@ -126,6 +126,14 @@
     #define CFG_TUSB_MEM_DCACHE_LINE_SIZE_DEFAULT 32
   #endif
 
+  // Errata ERR050101, listed for RT1015/RT1020/RT1024/RT1050 (no fix scheduled) and for
+  // RT1060/RT1064 rev A (fixed in rev B); not listed for RT1010 or the RT11xx family.
+  #if defined(MIMXRT1015_SERIES) || defined(MIMXRT1021_SERIES) || defined(MIMXRT1024_SERIES) || \
+      defined(MIMXRT1051_SERIES) || defined(MIMXRT1052_SERIES) || defined(MIMXRT1061_SERIES) || \
+      defined(MIMXRT1062_SERIES) || defined(MIMXRT1064_SERIES)
+    #define CFG_TUSB_MIMXRT1XXX_ERRATA_ERR050101 1
+  #endif
+
 #elif TU_CHECK_MCU(OPT_MCU_KINETIS_KL, OPT_MCU_KINETIS_K32L, OPT_MCU_KINETIS_K)
   #define TUP_USBIP_CHIPIDEA_FS
   #define TUP_USBIP_CHIPIDEA_FS_KINETIS
@@ -768,6 +776,17 @@
   #define TUP_DCD_EDPT_ISO_ALLOC
 #endif
 
+// Set by silicon whose isochronous IN endpoint can be unprimed by an IN token sent to that same
+// endpoint number on ANOTHER device sharing the host, taking one of this device's OUT endpoints
+// down with it - undetectable in software. Descriptors must then give an isochronous IN endpoint
+// a number no other device on the bus uses; a number is only safe while it stays unique, so two
+// affected boards on one hub must not pick the same one. Default 0 (no such conflict). Set it to
+// 0 by hand on RT1060/RT1064 rev B, which carry the fix - the revision cannot be told apart at
+// compile time, so the affected parts are assumed to be rev A.
+#ifndef CFG_TUSB_MIMXRT1XXX_ERRATA_ERR050101
+  #define CFG_TUSB_MIMXRT1XXX_ERRATA_ERR050101 0
+#endif
+
 // Some USBIPs (SAMG, SAMX7X, PIC32, MAX3266x/MAX78002) cannot assign the same endpoint
 // number to both IN and OUT. Default to 0 (same endpoint number may be used for IN and OUT).
 #ifndef CFG_TUD_ENDPOINT_ONE_DIRECTION_ONLY