i2c: qup: Vote for interconnect bandwidth to DRAM

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When the I2C QUP controller is used together with a DMA engine it needs
to vote for the interconnect path to the DRAM. Otherwise it may be
unable to access the memory quickly enough.

The requested peak bandwidth is dependent on the I2C core clock.

To avoid sending votes too often the bandwidth is always requested when
a DMA transfer starts, but dropped only on runtime suspend. Runtime
suspend should only happen if no transfer is active. After resumption we
can defer the next vote until the first DMA transfer actually happens.

The implementation is largely identical to the one introduced for
spi-qup in commit ecdaa94730 ("spi: qup: Vote for interconnect
bandwidth to DRAM") since both drivers represent the same hardware
block.

Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20231128-i2c-qup-dvfs-v1-3-59a0e3039111@kernkonzept.com

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Stephan Gerhold 2023-11-28 10:48:37 +01:00 • committed by Andi Shyti

parent d15971447f

commit d4f35233a6

1 changed files with 36 additions and 0 deletions

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drivers/i2c/busses/i2c-qup.c

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