[PATCH] fpga: zynq-fpga: Ensure proper xCAP interface switch

From: Nava kishore Manne <nava.kishore.manne@amd.com>
To: <mdf@kernel.org>, <hao.wu@intel.com>, <yilun.xu@intel.com>,
	<trix@redhat.com>, <michal.simek@amd.com>,
	<linux-fpga@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>
Cc: Alfonso Rodriguez <alfonso.rodriguezm@upm.es>
Subject: [PATCH] fpga: zynq-fpga: Ensure proper xCAP interface switch
Date: Fri, 19 May 2023 16:02:32 +0530	[thread overview]
Message-ID: <20230519103232.3009096-1-nava.kishore.manne@amd.com> (raw)

From: Alfonso Rodriguez <alfonso.rodriguezm@upm.es>

Ensure that the low-level fpga-manager driver for Zynq-7000 devices
switches between reconfiguration interfaces as specified in the TRM
(section 6.5.1: "Ensure that all outstanding transactions are completed
before changing interfaces"); device (re)configuration may fail otherwise

Signed-off-by: Alfonso Rodriguez <alfonso.rodriguezm@upm.es>
Tested-by: Nava kishore Manne <nava.kishore.manne@amd.com>
---
 drivers/fpga/zynq-fpga.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/fpga/zynq-fpga.c b/drivers/fpga/zynq-fpga.c
index ae0da361e6c6..88db9ac36887 100644
--- a/drivers/fpga/zynq-fpga.c
+++ b/drivers/fpga/zynq-fpga.c
@@ -493,15 +493,16 @@ static int zynq_fpga_ops_write_complete(struct fpga_manager *mgr,
 	if (err)
 		return err;
 
-	/* Release 'PR' control back to the ICAP */
-	zynq_fpga_write(priv, CTRL_OFFSET,
-		zynq_fpga_read(priv, CTRL_OFFSET) & ~CTRL_PCAP_PR_MASK);
-
 	err = zynq_fpga_poll_timeout(priv, INT_STS_OFFSET, intr_status,
 				     intr_status & IXR_PCFG_DONE_MASK,
 				     INIT_POLL_DELAY,
 				     INIT_POLL_TIMEOUT);
 
+	/* Release 'PR' control back to the ICAP */
+	zynq_fpga_write(priv, CTRL_OFFSET,
+			zynq_fpga_read(priv, CTRL_OFFSET)
+			& ~CTRL_PCAP_PR_MASK);
+
 	clk_disable(priv->clk);
 
 	if (err)
-- 
2.25.1

