[Trusty][PATCH] mfd: rtsx_pcr: Fix MSI enable error handling

[Adam Lee]

From: Chris Ball <chris at printf.net>

BugLink: http://bugs.launchpad.net/bugs/1366841

pci_enable_msi() can return failure with both positive and negative
integers -- it returns 0 for success -- but is only tested here for
"if (ret < 0)".  This causes us to try to use MSI on the RTS5249 SD
reader in the Dell XPS 11 when enabling MSI failed, causing:

[    1.737110] rtsx_pci: probe of 0000:05:00.0 failed with error -110

Cc: stable <stable at vger.kernel.org>
Reported-by: D. Jared Dominguez <Jared_Dominguez at Dell.com>
Tested-by: D. Jared Dominguez <Jared_Dominguez at Dell.com>
Signed-off-by: Chris Ball <chris at printf.net>
Signed-off-by: Lee Jones <lee.jones at linaro.org>
(cherry picked from commit 5152970538a5e16c03bbcb9f1c780489a795ed40)
Signed-off-by: Adam Lee <adam.lee at canonical.com>
---
 drivers/mfd/rtsx_pcr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/rtsx_pcr.c b/drivers/mfd/rtsx_pcr.c
index d8ab56d..e1b8126 100644
--- a/drivers/mfd/rtsx_pcr.c
+++ b/drivers/mfd/rtsx_pcr.c
@@ -1177,7 +1177,7 @@ static int rtsx_pci_probe(struct pci_dev *pcidev,
 	pcr->msi_en = msi_en;
 	if (pcr->msi_en) {
 		ret = pci_enable_msi(pcidev);
-		if (ret < 0)
+		if (ret)
 			pcr->msi_en = false;
 	}
 
-- 
2.1.1