Applied "spi: rockchip: limit transfers to (64K - 1) bytes" to the spi tree

Brian Norris briannorris at
Wed Jul 20 10:01:52 PDT 2016

Hi Mark,

On Wed, Jul 20, 2016 at 05:44:04PM +0100, Mark Brown wrote:
> The patch
>    spi: rockchip: limit transfers to (64K - 1) bytes
> has been applied to the spi tree at
>    git:// 
> All being well this means that it will be integrated into the linux-next
> tree (usually sometime in the next 24 hours) and sent to Linus during
> the next merge window (or sooner if it is a bug fix), however if
> problems are discovered then the patch may be dropped or reverted.  
> You may get further e-mails resulting from automated or manual testing
> and review of the tree, please engage with people reporting problems and
> send followup patches addressing any issues that are reported if needed.
> If any updates are required or you are submitting further changes they
> should be sent as incremental updates against current git, existing
> patches will not be replaced.
> Please add any relevant lists and maintainers to the CCs when replying
> to this mail.
> Thanks,
> Mark
> From 5185a81c02d4118b11e6cb7b5fbf6f15ff7aff90 Mon Sep 17 00:00:00 2001
> From: Brian Norris <briannorris at>
> Date: Thu, 14 Jul 2016 18:30:59 -0700
> Subject: [PATCH] spi: rockchip: limit transfers to (64K - 1) bytes
> The Rockchip SPI controller's length register only supports 16-bits,
> yielding a maximum length of 64KiB (the CTRLR1 register holds "length -
> 1"). Trying to transfer more than that (e.g., with a large SPI flash
> read) will cause the driver to hang.
> Now, it seems that while theoretically we should be able to program
> CTRLR1 with 0xffff, and get a 64KiB transfer, but that also seems to
> cause the core to choke, so stick with a maximum of 64K - 1 bytes --
> i.e., 0xffff.
> Signed-off-by: Brian Norris <briannorris at>
> Signed-off-by: Mark Brown <broonie at>

Thanks for applying! I'm OK with that, but just to be clear this might
qualify as a (very slight) hack, since I believe we should be able to
support a full 64KiB on both PIO and DMA. But it is better than the
current state of things on this driver, IMO. I suppose it's up to
Rockchip (or me) to figure out why some PIO transfers fail at exactly
64K if we want to support that. They have reproduced the failures I've


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