From 14dd37fc7b65f6f7e362d44acad4603d4db4821d Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Fri, 9 Mar 2018 10:44:13 -0800
Subject: [PATCH] staging: vc04_services: Remove cache-line-size property (v3)
Git-commit: 14dd37fc7b65f6f7e362d44acad4603d4db4821d
Patch-mainline: v4.17-rc1
References: FATE#324827

It's been tempting to replace this with (L1) cache_line_size(), but
that's really not what the value is about.  It's about coordinating
the condition for the pagelist fragment behavior between the two
sides.  However, the property was not accepted for the upstream DT
binding, so we have to use the firmware's fallback value.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c |   20 +++++-----
 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_pagelist.h |    1 
 2 files changed, 11 insertions(+), 10 deletions(-)

--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
@@ -77,7 +77,17 @@ struct vchiq_pagelist_info {
 };
 
 static void __iomem *g_regs;
-static unsigned int g_cache_line_size = sizeof(CACHE_LINE_SIZE);
+/* This value is the size of the L2 cache lines as understood by the
+ * VPU firmware, which determines the required alignment of the
+ * offsets/sizes in pagelists.
+ *
+ * Modern VPU firmware looks for a DT "cache-line-size" property in
+ * the VCHIQ node and will overwrite it with the actual L2 cache size,
+ * which the kernel must then respect.  That property was rejected
+ * upstream, so we have to use the VPU firmware's compatibility value
+ * of 32.
+ */
+static unsigned int g_cache_line_size = 32;
 static unsigned int g_fragments_size;
 static char *g_fragments_base;
 static char *g_free_fragments;
@@ -117,14 +127,6 @@ int vchiq_platform_init(struct platform_
 	if (err < 0)
 		return err;
 
-	err = of_property_read_u32(dev->of_node, "cache-line-size",
-				   &g_cache_line_size);
-
-	if (err) {
-		dev_err(dev, "Missing cache-line-size property\n");
-		return -ENODEV;
-	}
-
 	g_fragments_size = 2 * g_cache_line_size;
 
 	/* Allocate space for the channels in coherent memory */
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_pagelist.h
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_pagelist.h
@@ -34,7 +34,6 @@
 #ifndef VCHIQ_PAGELIST_H
 #define VCHIQ_PAGELIST_H
 
-#define CACHE_LINE_SIZE 32
 #define PAGELIST_WRITE 0
 #define PAGELIST_READ 1
 #define PAGELIST_READ_WITH_FRAGMENTS 2