Re: [PATCH 3/3] PCI: mediatek-gen3: Move reset/assert callbacks in .power_up()

["lorenzo@kernel.org" <lorenzo@kernel.org>]

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On Nov 08, Bjorn Helgaas wrote:
> On Fri, Nov 08, 2024 at 02:51:15AM +0000, Jianjun Wang (王建军) wrote:
> > On Thu, 2024-11-07 at 10:21 -0600, Bjorn Helgaas wrote:
> > > On Thu, Nov 07, 2024 at 05:08:55PM +0100, Lorenzo Bianconi wrote:
> > > > > On Thu, Nov 07, 2024 at 02:50:55PM +0100, Lorenzo Bianconi wrote:
> > > > > > In order to make the code more readable, move phy and mac
> > > > > > reset lines assert/de-assert configuration in .power_up
> > > > > > callback (mtk_pcie_en7581_power_up/mtk_pcie_power_up).
> > > > 
> > > > ...
> > > > > Is there a requirement that the PHY and MAC reset ordering be
> > > > > different for EN7581 vs other chips?
> > > > > 
> > > > > EN7581:
> > > > > 
> > > > >   assert PHY reset
> > > > >   assert MAC reset
> > > > >   power on PHY
> > > > >   deassert PHY reset
> > > > >   deassert MAC reset
> > > > > 
> > > > > others:
> > > > > 
> > > > >   assert PHY reset
> > > > >   assert MAC reset
> > > > >   deassert PHY reset
> > > > >   power on PHY
> > > > >   deassert MAC reset
> > > > > 
> > > > > Is there one order that would work for both?
> > > > 
> > > > EN7581 requires to run phy_init()/phy_power_on() before deassert
> > > > PHY reset lines.
> > > 
> > > And the other chips require the PHY power-on to be *after*
> > > deasserting PHY reset?
> > 
> > For MediaTek's chips, the reset will clear all register values and
> > reset the hardware state. Therefore, we can only initialize and
> > power-on the MAC and PHY after deasserting their resets.
> 
> OK, it sounds like you're saying the Airoha EN7581 is not a MediaTek
> chip and does require a different ordering of PHY reset deassert and
> PHY power-on:
> 
>   - EN7581 requires PHY power-on before PHY reset deassert,
> 
>   - other chips require PHY reset deassert before PHY power-on.
> 
> That's fine and probably worth a short comment in
> mtk_pcie_en7581_power_up(), e.g., "Unlike the MediaTek controllers,
> the Airoha EN7581 requires PHY power-on before PHY reset deassert".
> 
> Bjorn

ack, I will add it.

Regards,
Lorenzo

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