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Message-Id: <1471263690-32512-1-git-send-email-zajec5@gmail.com>
Date: Mon, 15 Aug 2016 14:21:28 +0200
From: Rafał Miłecki <zajec5@...il.com>
To: Brian Norris <computersforpeace@...il.com>,
linux-mtd@...ts.infradead.org
Cc: Rafał Miłecki <rafal@...ecki.pl>,
David Woodhouse <dwmw2@...radead.org>,
Frans Klaver <fransklaver@...il.com>,
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] mtd: bcm47xxsflash: use uncached MMIO access for BCM53573
From: Rafał Miłecki <rafal@...ecki.pl>
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@...ecki.pl>
---
drivers/mtd/devices/bcm47xxsflash.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/devices/bcm47xxsflash.c b/drivers/mtd/devices/bcm47xxsflash.c
index 1c65c15..514be04 100644
--- a/drivers/mtd/devices/bcm47xxsflash.c
+++ b/drivers/mtd/devices/bcm47xxsflash.c
@@ -296,16 +296,30 @@ static int bcm47xxsflash_bcma_probe(struct platform_device *pdev)
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;
--
1.8.4.5
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