drm/omap: fix TILER on OMAP5

On OMAP5 it is not possible to use TILER buffer with CPU when caching or
write-combining is used. Doing so leads to errors from the memory
manager.

However, on OMAP4, write-combining works fine.

This patch adds platform specific data for the TILER, and a function
tiler_get_cpu_cache_flags() which can be used to get the caching mode to
be used.

Note that without write-combining the use of the TILER buffer with CPU
is unusably slow. It's still good to have it operational for testing
purposes.

Signed-off-by: Tomi Valkeinen <[e-mail]>

drivers/gpu/drm/omapdrm/omap_dmm_priv.h

···
 	struct list_head idle_node;
 };
 
+struct dmm_platform_data {
+	uint32_t cpu_cache_flags;
+};
+
 struct dmm {
 	struct device *dev;
 	void __iomem *base;
···
 
 	/* allocation list and lock */
 	struct list_head alloc_head;
+
+	const struct dmm_platform_data *plat_data;
 };
 
 #endif

drivers/gpu/drm/omapdrm/omap_dmm_tiler.c

···
 static struct tcm *containers[TILFMT_NFORMATS];
 static struct dmm *omap_dmm;
 
+#if defined(CONFIG_OF)
+static const struct of_device_id dmm_of_match[];
+#endif
+
 /* global spinlock for protecting lists */
 static DEFINE_SPINLOCK(list_lock);
 
···
 	return round_up(geom[fmt].cpp * w, PAGE_SIZE) * h;
 }
 
+uint32_t tiler_get_cpu_cache_flags(void)
+{
+	return omap_dmm->plat_data->cpu_cache_flags;
+}
+
 bool dmm_is_available(void)
 {
 	return omap_dmm ? true : false;
···
 	INIT_LIST_HEAD(&omap_dmm->idle_head);
 
 	init_waitqueue_head(&omap_dmm->engine_queue);
+
+	if (dev->dev.of_node) {
+		const struct of_device_id *match;
+
+		match = of_match_node(dmm_of_match, dev->dev.of_node);
+		if (!match) {
+			dev_err(&dev->dev, "failed to find matching device node\n");
+			return -ENODEV;
+		}
+
+		omap_dmm->plat_data = match->data;
+	}
 
 	/* lookup hwmod data - base address and irq */
 	mem = platform_get_resource(dev, IORESOURCE_MEM, 0);
···
 #endif
 
 #if defined(CONFIG_OF)
+static const struct dmm_platform_data dmm_omap4_platform_data = {
+	.cpu_cache_flags = OMAP_BO_WC,
+};
+
+static const struct dmm_platform_data dmm_omap5_platform_data = {
+	.cpu_cache_flags = OMAP_BO_UNCACHED,
+};
+
 static const struct of_device_id dmm_of_match[] = {
-	{ .compatible = "ti,omap4-dmm", },
-	{ .compatible = "ti,omap5-dmm", },
+	{
+		.compatible = "ti,omap4-dmm",
+		.data = &dmm_omap4_platform_data,
+	},
+	{
+		.compatible = "ti,omap5-dmm",
+		.data = &dmm_omap5_platform_data,
+	},
 	{},
 };
 #endif

drivers/gpu/drm/omapdrm/omap_dmm_tiler.h

···
 size_t tiler_size(enum tiler_fmt fmt, uint16_t w, uint16_t h);
 size_t tiler_vsize(enum tiler_fmt fmt, uint16_t w, uint16_t h);
 void tiler_align(enum tiler_fmt fmt, uint16_t *w, uint16_t *h);
+uint32_t tiler_get_cpu_cache_flags(void);
 bool dmm_is_available(void);
 
 extern struct platform_driver omap_dmm_driver;

drivers/gpu/drm/omapdrm/omap_gem.c

···
 		/* currently don't allow cached buffers.. there is some caching
 		 * stuff that needs to be handled better
 		 */
-		flags &= ~(OMAP_BO_CACHED|OMAP_BO_UNCACHED);
-		flags |= OMAP_BO_WC;
+		flags &= ~(OMAP_BO_CACHED|OMAP_BO_WC|OMAP_BO_UNCACHED);
+		flags |= tiler_get_cpu_cache_flags();
 
 		/* align dimensions to slot boundaries... */
 		tiler_align(gem2fmt(flags),