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Date: Mon, 7 Nov 2016 10:41:56 +0100 From: Boris Brezillon <boris.brezillon@...e-electrons.com> To: Rafał Miłecki <zajec5@...il.com> Cc: Brian Norris <computersforpeace@...il.com>, linux-mtd@...ts.infradead.org, Rafał Miłecki <rafal@...ecki.pl>, Frans Klaver <fransklaver@...il.com>, David Woodhouse <dwmw2@...radead.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] mtd: bcm47xxsflash: use uncached MMIO access for BCM53573 On Mon, 15 Aug 2016 14:21:28 +0200 Rafał Miłecki <zajec5@...il.com> wrote: > 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> Reviewed-by: Boris Brezillon <boris.brezillon@...e-electrons.com> > --- > 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;
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