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References: <20190417133941.22962-4-clg@kaod.org>
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Date: Thu, 18 Apr 2019 21:03:20 -0400
From: "Andrew Jeffery" <andrew@aj.id.au>
To: "Milton Miller II" <miltonm@us.ibm.com>,
 =?UTF-8?Q?C=C3=A9dric_Le_Goater?= <clg@kaod.org>
Cc: openbmc@lists.ozlabs.org
Subject: =?UTF-8?Q?Re:_[PATCH_dev-5.0_3/4]_mtd:_spi-nor:_aspeed:_use_memcpy=5Ffro?=
 =?UTF-8?Q?mio()_to_capture_the_optimization_buffer?=
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On Fri, 19 Apr 2019, at 06:53, Milton Miller II wrote:
> About 04/17/2019 09:20AM in some timezone, C=C3=A9dric Le Goater wrote=
:
>=20
>=20
> >aspeed_smc_read_from_ahb() only reads the first word which is not
> >what
> >we want. We want to capture a CALIBRATE_BUF_SIZE size window of the
> >flash contents to optimize the read.
> >
>=20
> NACK
>=20
> This justifcation is false.  The routine reads the whole buffer
> because it calls the _rep routine and takes the size.
>=20
> In addition, the comment just before aspeed_smc_read_from_ahb
> tells why memcpy_fromio and memcpy_toio are broken on 32 bit
> arm, and this is still the case judging from the recent bug
> reportfrom a Nuvaton user [1].
>=20
> [1] https://github.com/openbmc/openbmc/issues/3521
>=20
> Andrew, Please revert this patch.

Yeah, I had a briefly nagging thought about this when I applied it. I
should have gone with that gut instinct and inspected it in more
depth.

Thanks for calling it out.

Reverting for dev-5.0, this is an isolated issue (arguably should have
been separated from the current series).

Andrew

>=20
> >Signed-off-by: C=C3=A9dric Le Goater <clg@kaod.org>
> >---
> > drivers/mtd/spi-nor/aspeed-smc.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> >diff --git a/drivers/mtd/spi-nor/aspeed-smc.c
> >b/drivers/mtd/spi-nor/aspeed-smc.c
> >index 1437732fdea1..7e289ecb1c99 100644
> >--- a/drivers/mtd/spi-nor/aspeed-smc.c
> >+++ b/drivers/mtd/spi-nor/aspeed-smc.c
> >@@ -796,8 +796,7 @@ static bool aspeed_smc_check_reads(struct
> >aspeed_smc_chip *chip,
> > 	int i;
> >=20
> > 	for (i =3D 0; i < 10; i++) {
> >-		aspeed_smc_read_from_ahb(test_buf, chip->ahb_base,
> >-					 CALIBRATE_BUF_SIZE);
> >+		memcpy_fromio(test_buf, chip->ahb_base, CALIBRATE_BUF_SIZE);
> > 		if (memcmp(test_buf, golden_buf, CALIBRATE_BUF_SIZE) !=3D 0)
> > 			return false;
> > 	}
> >@@ -921,8 +920,7 @@ static int aspeed_smc_optimize_read(struct
> >aspeed_smc_chip *chip,
> >=20
> > 	writel(chip->ctl_val[smc_read], chip->ctl);
> >=20
> >-	aspeed_smc_read_from_ahb(golden_buf, chip->ahb_base,
> >-				 CALIBRATE_BUF_SIZE);
> >+	memcpy_fromio(golden_buf, chip->ahb_base, CALIBRATE_BUF_SIZE);
> >=20
> > 	/* Establish our read mode with freq field set to 0 (HCLK/16) */
> > 	chip->ctl_val[smc_read] =3D save_read_val & 0xfffff0ff;
> >--=20
> >2.20.1
> >
> >
>=20
>