summaryrefslogtreecommitdiff
path: root/target/linux/generic/patches-4.4/143-mtd-bcm47xxsflash-use-uncached-MMIO-access-for-BCM53.patch
blob: 98c62caf5f686212166ef412e27d41084260610a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
From 77fab8f7dc756ba65f37145c493cc04f17e36bea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Mon, 15 Aug 2016 14:13:09 +0200
Subject: [PATCH] mtd: bcm47xxsflash: use uncached MMIO access for BCM53573
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

BCM53573 is a new series of Broadcom's SoCs. It's based on ARM and uses
this old ChipCommon-based flash access. Early tests resulted in flash
corruptions that were tracked down to using cached MMIO for flash read
access. Switch to ioremap_nocache conditionally to support BCM53573 and
don't break performance on old MIPS devices.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
 drivers/mtd/devices/bcm47xxsflash.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

--- a/drivers/mtd/devices/bcm47xxsflash.c
+++ b/drivers/mtd/devices/bcm47xxsflash.c
@@ -296,16 +296,30 @@ static int bcm47xxsflash_bcma_probe(stru
 		dev_err(dev, "can't request region for resource %pR\n", res);
 		return -EBUSY;
 	}
-	b47s->window = ioremap_cache(res->start, resource_size(res));
-	if (!b47s->window) {
-		dev_err(dev, "ioremap failed for resource %pR\n", res);
-		return -ENOMEM;
-	}
 
 	b47s->bcma_cc = container_of(sflash, struct bcma_drv_cc, sflash);
 	b47s->cc_read = bcm47xxsflash_bcma_cc_read;
 	b47s->cc_write = bcm47xxsflash_bcma_cc_write;
 
+	/*
+	 * On old MIPS devices cache was magically invalidated when needed,
+	 * allowing us to use cached access and gain some performance. Trying
+	 * the same on ARM based BCM53573 results in flash corruptions, we need
+	 * to use uncached access for it.
+	 *
+	 * It may be arch specific, but right now there is only 1 ARM SoC using
+	 * this driver, so let's follow Broadcom's reference code and check
+	 * ChipCommon revision.
+	 */
+	if (b47s->bcma_cc->core->id.rev == 54)
+		b47s->window = ioremap_nocache(res->start, resource_size(res));
+	else
+		b47s->window = ioremap_cache(res->start, resource_size(res));
+	if (!b47s->window) {
+		dev_err(dev, "ioremap failed for resource %pR\n", res);
+		return -ENOMEM;
+	}
+
 	switch (b47s->bcma_cc->capabilities & BCMA_CC_CAP_FLASHT) {
 	case BCMA_CC_FLASHT_STSER:
 		b47s->type = BCM47XXSFLASH_TYPE_ST;