platform-msi: Do not cache msi_desc in handler_data

The current implementation of platform MSI caches the msi_desc
pointer in irq_data::handler_data. This is a bit silly, as
we also have irq_data::msi_desc, which is perfectly valid.

Remove the useless assignment and simplify the whole flow.

Reported-by: Ma Jun <majun258@huawei.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Jiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/1442147824-20971-1-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/base/platform-msi.c

@@ -63,20 +63,8 @@ static int platform_msi_init(struct irq_domain *domain,
 			     unsigned int virq, irq_hw_number_t hwirq,
 			     msi_alloc_info_t *arg)
 {
-	struct irq_data *data;
-
-	irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
-				      info->chip, info->chip_data);
-
-	/*
-	 * Save the MSI descriptor in handler_data so that the
-	 * irq_write_msi_msg callback can retrieve it (and the
-	 * associated device).
-	 */
-	data = irq_domain_get_irq_data(domain, virq);
-	data->handler_data = arg->desc;
-
-	return 0;
+	return irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
+					     info->chip, info->chip_data);
 }
 #else
 #define platform_msi_set_desc		NULL
@@ -97,7 +85,7 @@ static void platform_msi_update_dom_ops(struct msi_domain_info *info)
 
 static void platform_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
 {
-	struct msi_desc *desc = irq_data_get_irq_handler_data(data);
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
 	struct platform_msi_priv_data *priv_data;
 
 	priv_data = desc->platform.msi_priv_data;