[PATCH v3] mtd: nand: brcmnand: Disable prefetch by default

[PATCH v3] mtd: nand: brcmnand: Disable prefetch by default

[Kamal Dasu]

Brcm nand controller prefetch feature needs to be disabled
by default. Enabling affects performance on random reads as
well as dma reads.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Fixes: 27c5b17cd1b1 ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
Cc: stable@vger.kernel.org
---
 drivers/mtd/nand/brcmnand/brcmnand.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
index dd56a67..2a978d9 100644
--- a/drivers/mtd/nand/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/brcmnand/brcmnand.c
@@ -2193,16 +2193,9 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
 	if (ctrl->nand_version >= 0x0702)
 		tmp |= ACC_CONTROL_RD_ERASED;
 	tmp &= ~ACC_CONTROL_FAST_PGM_RDIN;
-	if (ctrl->features & BRCMNAND_HAS_PREFETCH) {
-		/*
-		 * FIXME: Flash DMA + prefetch may see spurious erased-page ECC
-		 * errors
-		 */
-		if (has_flash_dma(ctrl))
-			tmp &= ~ACC_CONTROL_PREFETCH;
-		else
-			tmp |= ACC_CONTROL_PREFETCH;
-	}
+	if (ctrl->features & BRCMNAND_HAS_PREFETCH)
+		tmp &= ~ACC_CONTROL_PREFETCH;
+
 	nand_writereg(ctrl, offs, tmp);
 
 	return 0;
-- 
2.7.4

Re: [PATCH v3] mtd: nand: brcmnand: Disable prefetch by default

[Florian Fainelli]

On 01/08/2018 12:36 PM, Kamal Dasu wrote:
> Brcm nand controller prefetch feature needs to be disabled
> by default. Enabling affects performance on random reads as
> well as dma reads.
> 
> Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
> Fixes: 27c5b17cd1b1 ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
> Cc: stable@vger.kernel.org

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian

Re: [PATCH v3] mtd: nand: brcmnand: Disable prefetch by default

[Florian Fainelli]

On 01/08/2018 12:36 PM, Kamal Dasu wrote:
> Brcm nand controller prefetch feature needs to be disabled
> by default. Enabling affects performance on random reads as
> well as dma reads.
> 
> Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
> Fixes: 27c5b17cd1b1 ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
> Cc: stable@vger.kernel.org

Boris, is there a reason this is not in your v4.16 pull request? If not,
could you take that fix?

Thank you
-- 
Florian

Re: [PATCH v3] mtd: nand: brcmnand: Disable prefetch by default

[Boris Brezillon]

On Sat, 20 Jan 2018 15:13:35 -0800
Florian Fainelli <f.fainelli@gmail.com> wrote:

> On 01/08/2018 12:36 PM, Kamal Dasu wrote:
> > Brcm nand controller prefetch feature needs to be disabled
> > by default. Enabling affects performance on random reads as
> > well as dma reads.
> > 
> > Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
> > Fixes: 27c5b17cd1b1 ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
> > Cc: stable@vger.kernel.org  
> 
> Boris, is there a reason this is not in your v4.16 pull request?

Look carefully, it is there ;-).

"
Kamal Dasu (1):
      mtd: nand: brcmnand: Disable prefetch by default
"

> If not, could you take that fix?
> 
> Thank you

Re: [PATCH v3] mtd: nand: brcmnand: Disable prefetch by default

[Florian Fainelli]

On 01/20/2018 03:53 PM, Boris Brezillon wrote:
> On Sat, 20 Jan 2018 15:13:35 -0800
> Florian Fainelli <f.fainelli@gmail.com> wrote:
> 
>> On 01/08/2018 12:36 PM, Kamal Dasu wrote:
>>> Brcm nand controller prefetch feature needs to be disabled
>>> by default. Enabling affects performance on random reads as
>>> well as dma reads.
>>>
>>> Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
>>> Fixes: 27c5b17cd1b1 ("mtd: nand: add NAND driver "library" for Broadcom STB NAND controller")
>>> Cc: stable@vger.kernel.org  
>>
>> Boris, is there a reason this is not in your v4.16 pull request?
> 
> Look carefully, it is there ;-).

Indeed, I can't read, my bad.
-- 
Florian