Re: [PATCH v5 2/2] PCI: rockchip-host: Make the PERST# inactive delay configurable

[sashiko-bot@kernel.org]

> rockchip_pcie_host_init_port() waits T_PVPERL, 100 ms, before releasing
> PERST#. The GPIO is acquired with GPIOD_OUT_LOW early in probe, so PERST#
> is already asserted when that wait starts, and the wait therefore sets the
> reset pulse width as well.
> 
> That suits a board which powers the slot at the moment it asserts PERST#,
> but endpoints do not agree on what they want. On a ROCK Pi 4C carrying a
> JMB585 SATA controller, a pulse that long stops the endpoint answering
> configuration reads at all. Measured on that board with a single kernel and
> two module parameters, one sleeping before the GPIO is acquired and one in
> place of the wait, timing the pulse with a ktime delta across the two
> gpiod_set_value() calls:
> 
>   pre (ms)  post (ms)  pulse      trials  enumerated
>   0         0          1-11 ms    5       5
> [ ... ]
> specification sets, which covers T_PERST and T_PERST-CLK.
> 
> Suggested-by: Shawn Lin <shawn.lin@rock-chips.com>
> Link: https://lore.kernel.org/all/95aeecc0-2794-4cc6-a635-5c042afc1405@rock-chips.com/
> Signed-off-by: Enrique Hernández Bello <ehbello@gmail.com>

Sashiko has reviewed this patch and found no issues.

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