linux-kernel - [PATCH 3.16 168/254] sh_eth: fix TSU resource handling

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Date:   Wed, 28 Feb 2018 15:20:18 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
        "Sergei Shtylyov" <sergei.shtylyov@...entembedded.com>,
        "Nobuhiro Iwamatsu" <nobuhiro.iwamatsu.yj@...esas.com>
Subject: [PATCH 3.16 168/254] sh_eth: fix TSU resource handling

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>

commit dfe8266b8dd10e12a731c985b725fcf7f0e537f0 upstream.

When switching  the driver to the managed device API,  I managed to break
the  case of a  dual Ether devices sharing a single TSU: the 2nd Ether port
wouldn't probe. Iwamatsu-san has tried to fix this but his patch was buggy
and he then dropped the ball...

The solution is to  limit calling devm_request_mem_region() to the first
of  the two  ports  sharing the same TSU, so devm_ioremap_resource() can't
be used anymore for the TSU resource...

Fixes: d5e07e69218f ("sh_eth: use managed device API")
Reported-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@...esas.com>
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/net/ethernet/renesas/sh_eth.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -2873,10 +2873,29 @@ static int sh_eth_drv_probe(struct platf
 	/* ioremap the TSU registers */
 	if (mdp->cd->tsu) {
 		struct resource *rtsu;
+
 		rtsu = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-		mdp->tsu_addr = devm_ioremap_resource(&pdev->dev, rtsu);
-		if (IS_ERR(mdp->tsu_addr)) {
-			ret = PTR_ERR(mdp->tsu_addr);
+		if (!rtsu) {
+			dev_err(&pdev->dev, "no TSU resource\n");
+			ret = -ENODEV;
+			goto out_release;
+		}
+		/* We can only request the  TSU region  for the first port
+		 * of the two  sharing this TSU for the probe to succeed...
+		 */
+		if (devno % 2 == 0 &&
+		    !devm_request_mem_region(&pdev->dev, rtsu->start,
+					     resource_size(rtsu),
+					     dev_name(&pdev->dev))) {
+			dev_err(&pdev->dev, "can't request TSU resource.\n");
+			ret = -EBUSY;
+			goto out_release;
+		}
+		mdp->tsu_addr = devm_ioremap(&pdev->dev, rtsu->start,
+					     resource_size(rtsu));
+		if (!mdp->tsu_addr) {
+			dev_err(&pdev->dev, "TSU region ioremap() failed.\n");
+			ret = -ENOMEM;
 			goto out_release;
 		}
 		mdp->port = devno % 2;