From 3d2f617d448f5e1d15d2844b803c13763ed51f1f Mon Sep 17 00:00:00 2001 From: Uma Krishnan Date: Mon, 28 Nov 2016 18:41:36 -0600 Subject: [PATCH] scsi: cxlflash: Improve context_reset() logic Currently, the context reset routine waits for command room to be available before sending the reset request. Per review of the SISLite specification and clarifications from the CXL Flash AFU designers, this wait is unnecessary. The reset request can be sent anytime regardless of command room, so long as only a single reset request is active at any one point in time. This commit simplifies the reset routine by removing the wait for command room. Additionally it adds a debug trace to help pinpoint hardware errors when a context reset does not complete. Signed-off-by: Uma Krishnan Acked-by: Matthew R. Ochs Signed-off-by: Martin K. Petersen --- drivers/scsi/cxlflash/main.c | 23 +++++------------------ 1 file changed, 5 insertions(+), 18 deletions(-) diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c index 600486066a9f..6d33d8c3a9fc 100644 --- a/drivers/scsi/cxlflash/main.c +++ b/drivers/scsi/cxlflash/main.c @@ -263,8 +263,9 @@ static void context_reset(struct afu_cmd *cmd) { int nretry = 0; u64 rrin = 0x1; - u64 room = 0; struct afu *afu = cmd->parent; + struct cxlflash_cfg *cfg = afu->parent; + struct device *dev = &cfg->dev->dev; ulong lock_flags; pr_debug("%s: cmd=%p\n", __func__, cmd); @@ -280,23 +281,6 @@ static void context_reset(struct afu_cmd *cmd) cmd->sa.host_use_b[0] |= (B_DONE | B_ERROR | B_TIMEOUT); spin_unlock_irqrestore(&cmd->slock, lock_flags); - /* - * We really want to send this reset at all costs, so spread - * out wait time on successive retries for available room. - */ - do { - room = readq_be(&afu->host_map->cmd_room); - atomic64_set(&afu->room, room); - if (room) - goto write_rrin; - udelay(1 << nretry); - } while (nretry++ < MC_ROOM_RETRY_CNT); - - pr_err("%s: no cmd_room to send reset\n", __func__); - return; - -write_rrin: - nretry = 0; writeq_be(rrin, &afu->host_map->ioarrin); do { rrin = readq_be(&afu->host_map->ioarrin); @@ -305,6 +289,9 @@ write_rrin: /* Double delay each time */ udelay(1 << nretry); } while (nretry++ < MC_ROOM_RETRY_CNT); + + dev_dbg(dev, "%s: returning rrin=0x%016llX nretry=%d\n", + __func__, rrin, nretry); } /** -- 2.20.1