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kernel: add BCM53573 flash fix sent upstream

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This fixes flash corruptions. It touches bcm47xxsflash driver shared
between brcm47xx and bcm53xx so put it in generic.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
This commit is contained in:
Rafał Miłecki 2016-08-16 22:33:21 +02:00
parent 13e20e6956
commit 2803527237
1 changed files with 57 additions and 0 deletions
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57
target/linux/generic/patches-4.4/143-mtd-bcm47xxsflash-use-uncached-MMIO-access-for-BCM53.patch Normal file
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@ -0,0 +1,57 @@
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;