From e761222593a1ae932cddbc81239b6a7cd98ddb70 Mon Sep 17 00:00:00 2001 From: Vipin K Parashar Date: Mon, 6 Jun 2016 14:56:37 +0530 Subject: hw/xscom: Reset XSCOM engine after finite number of retries when busy OPAL retries XSCOM read/write operations forever till it succeeds. This can cause XSCOM ops to hang forever when XSCOM engine remains busy for some reason. Changed it to retry XSCOM operations only XSCOM_BUSY_MAX_RETRIES number of times instead of retrying forever. Also added logic to reset XSCOM engine after XSCOM_BUSY_RESET_THRESHOLD number of retries to unblock it when it remains busy. Cc: stable # 9c2d82394fd2 ("xscom: Return OPAL_WRONG_STATE on XSCOM ops..") Signed-off-by: Vipin K Parashar Signed-off-by: Vaidyanathan Srinivasan Signed-off-by: Stewart Smith --- hw/xscom.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 57 insertions(+), 17 deletions(-) (limited to 'hw/xscom.c') diff --git a/hw/xscom.c b/hw/xscom.c index 4d88ce5..2a91a7b 100644 --- a/hw/xscom.c +++ b/hw/xscom.c @@ -23,6 +23,7 @@ #include #include #include +#include /* Mask of bits to clear in HMER before an access */ #define HMER_CLR_MASK (~(SPR_HMER_XSCOM_FAIL | \ @@ -41,6 +42,10 @@ DEFINE_LOG_ENTRY(OPAL_RC_XSCOM_RESET, OPAL_PLATFORM_ERR_EVT, OPAL_XSCOM, OPAL_CEC_HARDWARE, OPAL_PREDICTIVE_ERR_GENERAL, OPAL_NA); +DEFINE_LOG_ENTRY(OPAL_RC_XSCOM_BUSY, OPAL_PLATFORM_ERR_EVT, OPAL_XSCOM, + OPAL_CEC_HARDWARE, OPAL_PREDICTIVE_ERR_GENERAL, + OPAL_NA); + /* xscom details to trigger xstop */ static struct { uint64_t addr; @@ -118,18 +123,49 @@ static void xscom_reset(uint32_t gcid) */ } -static int xscom_handle_error(uint64_t hmer, uint32_t gcid, uint32_t pcb_addr, - bool is_write) +static int64_t xscom_handle_error(uint64_t hmer, uint32_t gcid, uint32_t pcb_addr, + bool is_write, int64_t retries) { + struct timespec ts; unsigned int stat = GETFIELD(SPR_HMER_XSCOM_STATUS, hmer); /* XXX Figure out error codes from doc and error * recovery procedures */ switch(stat) { - /* XSCOM blocked, just retry */ + /* + * XSCOM engine is blocked, need to retry. Reset XSCOM engine + * after crossing retry threshold before retrying again. + */ case 1: + if (retries && !(retries % XSCOM_BUSY_RESET_THRESHOLD)) { + prlog(PR_NOTICE, "XSCOM: Busy even after %d retries, " + "resetting XSCOM now. Total retries = %lld\n", + XSCOM_BUSY_RESET_THRESHOLD, retries); + xscom_reset(gcid); + + /* + * Its observed that sometimes immediate retry of + * XSCOM operation returns wrong data. Adding a + * delay for XSCOM reset to be effective. Delay of + * 10 ms is found to be working fine experimentally. + * FIXME: Replace 10ms delay by exact delay needed + * or other alternate method to confirm XSCOM reset + * completion, after checking from HW folks. + */ + ts.tv_sec = 0; + ts.tv_nsec = 10 * 1000; + nanosleep_nopoll(&ts, NULL); + } + + /* Log error if we have retried enough and its still busy */ + if (retries == XSCOM_BUSY_MAX_RETRIES) + log_simple_error(&e_info(OPAL_RC_XSCOM_BUSY), + "XSCOM: %s-busy error gcid=0x%x pcb_addr=0x%x " + "stat=0x%x\n", is_write ? "write" : "read", + gcid, pcb_addr, stat); return OPAL_BUSY; + /* CPU is asleep, don't retry */ case 2: return OPAL_WRONG_STATE; @@ -178,14 +214,14 @@ static bool xscom_gcid_ok(uint32_t gcid) static int __xscom_read(uint32_t gcid, uint32_t pcb_addr, uint64_t *val) { uint64_t hmer; - int64_t ret; + int64_t ret, retries; if (!xscom_gcid_ok(gcid)) { prerror("%s: invalid XSCOM gcid 0x%x\n", __func__, gcid); return OPAL_PARAMETER; } - for (;;) { + for (retries = 0; retries <= XSCOM_BUSY_MAX_RETRIES; retries++) { /* Clear status bits in HMER (HMER is special * writing to it *ands* bits */ @@ -199,27 +235,29 @@ static int __xscom_read(uint32_t gcid, uint32_t pcb_addr, uint64_t *val) /* Check for error */ if (!(hmer & SPR_HMER_XSCOM_FAIL)) - break; + return OPAL_SUCCESS; /* Handle error and possibly eventually retry */ - ret = xscom_handle_error(hmer, gcid, pcb_addr, false); - if (ret == OPAL_HARDWARE || ret == OPAL_WRONG_STATE) - return ret; + ret = xscom_handle_error(hmer, gcid, pcb_addr, false, retries); + if (ret != OPAL_BUSY) + break; } - return OPAL_SUCCESS; + + prerror("XSCOM: Read failed, ret = %lld\n", ret); + return ret; } static int __xscom_write(uint32_t gcid, uint32_t pcb_addr, uint64_t val) { uint64_t hmer; - int64_t ret; + int64_t ret, retries = 0; if (!xscom_gcid_ok(gcid)) { prerror("%s: invalid XSCOM gcid 0x%x\n", __func__, gcid); return OPAL_PARAMETER; } - for (;;) { + for (retries = 0; retries <= XSCOM_BUSY_MAX_RETRIES; retries++) { /* Clear status bits in HMER (HMER is special * writing to it *ands* bits */ @@ -233,14 +271,16 @@ static int __xscom_write(uint32_t gcid, uint32_t pcb_addr, uint64_t val) /* Check for error */ if (!(hmer & SPR_HMER_XSCOM_FAIL)) - break; + return OPAL_SUCCESS; /* Handle error and possibly eventually retry */ - ret = xscom_handle_error(hmer, gcid, pcb_addr, true); - if (ret == OPAL_HARDWARE || ret == OPAL_WRONG_STATE) - return ret; + ret = xscom_handle_error(hmer, gcid, pcb_addr, true, retries); + if (ret != OPAL_BUSY) + break; } - return OPAL_SUCCESS; + + prerror("XSCOM: Write failed, ret = %lld\n", ret); + return ret; } /* -- cgit v1.1