drm: apple: iomfb: Align buffer size on unmap/free as well

Fixes failure to unmap buffers in dcpep_cb_unmap_piodma() due to the
unaligned size. Further along this causes kernel log splat when DCP
tries to map the buffers again since thye IOVA is still in use.
This causes no apparent issue although map_piodma callback signals an
errror and returns 0 (unmapped as DVA).

It's not clear why this presents only randomly. Possibly some build or
uninitialized memory triggers this unmap/free and immediate allocate/map
cycle in the DCP firmware. I never notices this with a clang-built kernel
on j314c. It showed with gcc build with the Fedora config at least on
6.8.8 based kernels. This did not reproduce on j375d.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/gpu/drm/apple/iomfb_template.c

@@ -322,7 +322,10 @@ static void dcpep_cb_unmap_piodma(struct apple_dcp *dcp,
 	}
 
 	/* use the piodma iommu domain to unmap from the right IOMMU */
-	iommu_unmap(dcp->iommu_dom, memdesc->dva, memdesc->size);
+	/* HACK: expect size to be 16K aligned since the iommu API only maps
+	 *       full pages
+	 */
+	iommu_unmap(dcp->iommu_dom, memdesc->dva, ALIGN(memdesc->size, SZ_16K));
 }
 
 /*
@@ -370,6 +373,7 @@ dcpep_cb_allocate_buffer(struct apple_dcp *dcp,
 static u8 dcpep_cb_release_mem_desc(struct apple_dcp *dcp, u32 *mem_desc_id)
 {
 	struct dcp_mem_descriptor *memdesc;
+	size_t size;
 	u32 id = *mem_desc_id;
 
 	if (id >= DCP_MAX_MAPPINGS) {
@@ -385,10 +389,9 @@ static u8 dcpep_cb_release_mem_desc(struct apple_dcp *dcp, u32 *mem_desc_id)
 	}
 
 	memdesc = &dcp->memdesc[id];
+	size = ALIGN(memdesc->size, SZ_16K);
 	if (memdesc->buf) {
-		dma_free_coherent(dcp->dev, memdesc->size, memdesc->buf,
-				  memdesc->dva);
-
+		dma_free_coherent(dcp->dev, size, memdesc->buf, memdesc->dva);
 		memdesc->buf = NULL;
 		memset(&memdesc->map, 0, sizeof(memdesc->map));
 	} else {