Messages in this thread | | | Date | Wed, 29 Nov 2017 11:07:25 +0000 | From | Lee Jones <> | Subject | Re: [PATCH 1/2] mfd: cros ec: spi: Don't send first message too soon |
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On Mon, 13 Nov 2017, Jon Hunter wrote:
> On the Tegra124 Nyan-Big chromebook the very first SPI message sent to > the EC is failing. > > The Tegra SPI driver configures the SPI chip-selects to be active-high > by default (and always has for many years). The EC SPI requires an > active-low chip-select and so the Tegra chip-select is reconfigured to > be active-low when the EC SPI driver calls spi_setup(). The problem is > that if the first SPI message to the EC is sent too soon after > reconfiguring the SPI chip-select, it fails. > > The EC SPI driver prevents back-to-back SPI messages being sent too > soon by keeping track of the time the last transfer was sent via the > variable 'last_transfer_ns'. To prevent the very first transfer being > sent too soon, initialise the 'last_transfer_ns' variable after calling > spi_setup() and before sending the first SPI message. > > Signed-off-by: Jon Hunter <jonathanh@nvidia.com> > --- > Looks like this issue has been around for several Linux releases now > and it just depends on timing if this issue is seen or not and so there > is no specific commit this fixes. However, would be good to include for > v4.15. > > drivers/mfd/cros_ec_spi.c | 1 + > 1 file changed, 1 insertion(+)
Applied, thanks.
-- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
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