FreeCalypso > hg > fc-tourmaline
view cdg-hybrid/sap/mmsms.pdf @ 220:0ed36de51973
ABB semaphore protection overhaul
The ABB semaphone protection logic that came with TCS211 from TI
was broken in several ways:
* Some semaphore-protected functions were called from Application_Initialize()
context. NU_Obtain_Semaphore() called with NU_SUSPEND fails with
NU_INVALID_SUSPEND in this context, but the return value wasn't checked,
and NU_Release_Semaphore() would be called unconditionally at the end.
The latter call would increment the semaphore count past 1, making the
semaphore no longer binary and thus no longer effective for resource
protection. The fix is to check the return value from NU_Obtain_Semaphore()
and skip the NU_Release_Semaphore() call if the semaphore wasn't properly
obtained.
* Some SPI hardware manipulation was being done before entering the semaphore-
protected critical section. The fix is to reorder the code: first obtain
the semaphore, then do everything else.
* In the corner case of L1/DSP recovery, l1_abb_power_on() would call some
non-semaphore-protected ABB & SPI init functions. The fix is to skip those
calls in the case of recovery.
* A few additional corner cases existed, all of which are fixed by making
ABB semaphore protection 100% consistent for all ABB functions and code paths.
There is still one remaining problem of priority inversion: suppose a low-
priority task calls an ABB function, and some medium-priority task just happens
to preempt right in the middle of that semaphore-protected ABB operation. Then
the high-priority SPI task is locked out for a non-deterministic time until
that medium-priority task finishes its work and goes back to sleep. This
priority inversion problem remains outstanding for now.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Mon, 26 Apr 2021 20:55:25 +0000 |
parents | 35f7a1dc9f7d |
children |
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;******************************************************************************** ;*** File : mmsms.pdf ;*** Creation : Wed Mar 11 09:58:22 CST 2009 ;*** XSLT Processor : Apache Software Foundation / http://xml.apache.org/xalan-j / supports XSLT-Ver: 1 ;*** Copyright : (c) Texas Instruments AG, Berlin Germany 2002 ;******************************************************************************** ;*** Document Type : Service Access Point Specification ;*** Document Name : mmsms ;*** Document No. : 6147.106.97.102 ;*** Document Date : 2002-07-19 ;*** Document Status: BEING_PROCESSED ;*** Document Author: HM ;******************************************************************************** PRAGMA SRC_FILE_TIME "Thu Nov 29 09:47:08 2007" PRAGMA LAST_MODIFIED "2002-07-19" PRAGMA ID_AND_VERSION "6147.106.97.102" CONST MAX_SDU_LEN 1 ; maximum service data unit length VALTAB VAL_ti VAL 0 - 6 "ms originated transaction" VAL 8 - 14 "ms originated transaction" VAL 7 TI_RES_MO "reserved" VAL 15 TI_RES_MT "reserved" VAR cause "MM cause" S VAR l_buf "length in bits" S VAR o_buf "offset in bits" S VAR buf "bit buffer" B VAR ti "transaction identifier" B VAL @p_mmsms - VAL_ti@ VAR d1 "dummy, not used" B VAR d2 "dummy, not used" B COMP sdu "Service Data Unit" { l_buf ; length in bits o_buf ; offset in bits buf [MAX_SDU_LEN] ; bit buffer } ; MMSMS_ESTABLISH_REQ 0x80000009 ; MMSMS_RELEASE_REQ 0x80010009 ; MMSMS_DATA_REQ 0x80020009 ; MMSMS_DATA_IND 0x80004009 ; MMSMS_ERROR_IND 0x80014009 ; MMSMS_ESTABLISH_CNF 0x80024009 ; MMSMS_ESTABLISH_IND 0x80034009 ; MMSMS_RELEASE_IND 0x80044009 ; MMSMS_UNITDATA_IND 0x80054009 PRIM MMSMS_ESTABLISH_REQ 0x80000009 { ti ; transaction identifier } PRIM MMSMS_RELEASE_REQ 0x80010009 { ti ; transaction identifier } PRIM MMSMS_DATA_REQ 0x80020009 { d1 ; dummy d2 ; dummy sdu ; service data unit } PRIM MMSMS_DATA_IND 0x80004009 { d1 ; dummy d2 ; dummy sdu ; service data unit } PRIM MMSMS_ERROR_IND 0x80014009 { ti ; transaction identifier cause ; error cause } PRIM MMSMS_ESTABLISH_CNF 0x80024009 { ti ; transaction identifier } PRIM MMSMS_ESTABLISH_IND 0x80034009 { d1 ; dummy d2 ; dummy sdu ; service data unit } PRIM MMSMS_RELEASE_IND 0x80044009 { ti ; transaction identifier cause ; release cause } PRIM MMSMS_UNITDATA_IND 0x80054009 { d1 ; dummy d2 ; dummy sdu ; service data unit }