[PATCH] ti-msgmgr: fix of_irq_get_byname() error check

[Sergei Shtylyov]

of_irq_get_byname() may  return 0 as well as negative error number on
failure,  while the driver only checks for the negative values. The driver
would then call request_irq(0, ...) in ti_msgmgr_queue_startup() and never
get a valid channel interrupt.

Check for 'qinst->irq <= 0' instead and return -ENXIO from
ti_msgmgr_queue_setup() and this fail the driver's probe iff
of_irq_get_byname() returned 0.

Fixes: aace66b170ce ("mailbox: Introduce TI message manager driver")
Signed-off-by: Sergei Shtylyov <sergei.shtyl...@cogentembedded.com>

---
 drivers/mailbox/ti-msgmgr.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux/drivers/mailbox/ti-msgmgr.c
===================================================================
--- linux.orig/drivers/mailbox/ti-msgmgr.c
+++ linux/drivers/mailbox/ti-msgmgr.c
@@ -444,12 +444,12 @@ static int ti_msgmgr_queue_setup(int idx
                         "rx_%03d", qinst->queue_id);
 
                qinst->irq = of_irq_get_byname(np, of_rx_irq_name);
-               if (qinst->irq < 0) {
+               if (qinst->irq <= 0) {
                        dev_crit(dev,
                                 "[%d]QID %d PID %d:No IRQ[%s]: %d\n",
                                 idx, qinst->queue_id, qinst->proxy_id,
                                 of_rx_irq_name, qinst->irq);
-                       return qinst->irq;
+                       return qinst->irq ?: -ENXIO;
                }
                /* Allocate usage buffer for rx */
                qinst->rx_buff = devm_kzalloc(dev,