linux-kernel - [PATCH] staging: fsl-mc/dpio: Fix early writing of valid bit

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Date:   Wed, 5 Apr 2017 08:24:17 -0500
From:   Ioana Radulescu <ruxandra.radulescu@....com>
To:     <gregkh@...uxfoundation.org>, <roy.pledge@....com>
CC:     <devel@...verdev.osuosl.org>, <linux-kernel@...r.kernel.org>,
        <stuyoder@...il.com>, <haiying.wang@....com>,
        <ruxandra.radulescu@....com>
Subject: [PATCH] staging: fsl-mc/dpio: Fix early writing of valid bit

Commands written to the QMan software portals have a valid
bit in the "verb" field of the command that, when set with
the right value, notifies the hardware that the command is
fully written and ready to be processed.

The "verb" field should be the last one to be written in the
swp command registers, after all other fields are filled in.
The current implementation doesn't follow this rule for all
commands, which may result in an incompletely configured
command being processed by the hardware. Enforce the correct
order of writes to avoid this situation.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@....com>
---
 drivers/staging/fsl-mc/bus/dpio/qbman-portal.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/fsl-mc/bus/dpio/qbman-portal.c b/drivers/staging/fsl-mc/bus/dpio/qbman-portal.c
index c75f546b24fa..2a3ea29d9b43 100644
--- a/drivers/staging/fsl-mc/bus/dpio/qbman-portal.c
+++ b/drivers/staging/fsl-mc/bus/dpio/qbman-portal.c
@@ -616,13 +616,16 @@ int qbman_swp_pull(struct qbman_swp *s, struct qbman_pull_desc *d)
 		return -EBUSY;
 	}
 	s->vdq.storage = (void *)d->rsp_addr_virt;
-	d->tok = QMAN_DQ_TOKEN_VALID;
 	p = qbman_get_cmd(s, QBMAN_CENA_SWP_VDQCR);
-	*p = *d;
+	p->numf = d->numf;
+	p->tok = QMAN_DQ_TOKEN_VALID;
+	p->dq_src = d->dq_src;
+	p->rsp_addr = d->rsp_addr;
+	p->rsp_addr_virt = d->rsp_addr_virt;
 	dma_wmb();
 
 	/* Set the verb byte, have to substitute in the valid-bit */
-	p->verb |= s->vdq.valid_bit;
+	p->verb = d->verb | s->vdq.valid_bit;
 	s->vdq.valid_bit ^= QB_VALID_BIT;
 
 	return 0;
@@ -1004,7 +1007,6 @@ int qbman_swp_CDAN_set(struct qbman_swp *s, u16 channelid,
 		return -EBUSY;
 
 	/* Encode the caller-provided attributes */
-	p->verb = 0;
 	p->ch = cpu_to_le16(channelid);
 	p->we = we_mask;
 	if (cdan_en)
-- 
2.11.0