linux-kernel - Re: [PATCH] mtd: revert "spi-nor: intel: provide a range for poll

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Date:   Thu, 11 Jun 2020 13:39:47 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Luis Alberto Herrera <luisalberto@...gle.com>
Cc:     tudor.ambarus@...rochip.com,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Jethro Beekman <jethro@...tanix.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: revert "spi-nor: intel: provide a range for
 poll_timout"

On Wed, Jun 10, 2020 at 10:46:49PM +0000, Luis Alberto Herrera wrote:
> This change reverts aba3a882a178: "mtd: spi-nor: intel: provide a range
> for poll_timout". That change introduces a performance regression when
> reading sequentially from flash. Logging calls to intel_spi_read without
> this change we get:
> 
> Start MTD read
> [   20.045527] intel_spi_read(from=1800000, len=400000)
> [   20.045527] intel_spi_read(from=1800000, len=400000)
> [  282.199274] intel_spi_read(from=1c00000, len=400000)
> [  282.199274] intel_spi_read(from=1c00000, len=400000)
> [  544.351528] intel_spi_read(from=2000000, len=400000)
> [  544.351528] intel_spi_read(from=2000000, len=400000)
> End MTD read
> 
> With this change:
> 
> Start MTD read
> [   21.942922] intel_spi_read(from=1c00000, len=400000)
> [   21.942922] intel_spi_read(from=1c00000, len=400000)
> [   23.784058] intel_spi_read(from=2000000, len=400000)
> [   23.784058] intel_spi_read(from=2000000, len=400000)
> [   25.625006] intel_spi_read(from=2400000, len=400000)
> [   25.625006] intel_spi_read(from=2400000, len=400000)
> End MTD read
> 
> Signed-off-by: Luis Alberto Herrera <luisalberto@...gle.com>

Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>