sh_eth: fix TSU resource handling

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@renesas.com>
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 3 deletions

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 75323000c364..1bdd67a8a869 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -3225,10 +3225,29 @@ static int sh_eth_drv_probe(struct platform_device *pdev)
         /* 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;