Re: [PATCH v3 2/2] PCI: rockchip-host: comment danger of 5.0 GT/s speed

[Geraldo Nascimento <geraldogabriel@gmail.com>]

On Wed, Feb 25, 2026 at 06:12:29PM -0600, Bjorn Helgaas wrote:
> On Wed, Feb 25, 2026 at 07:27:44PM -0300, Geraldo Nascimento wrote:
> > According to Rockchip sources, there is grave danger in enabling 5.0
> > GT/s speed for this core. Add a comment documenting this risk of
> > "catastrophic failure" and discouraging end-users from forcing
> > higher speed.
> 
> A comment in the code might be useful but doesn't discourage end
> users.

Hi Bjorn, thanks for the quick review.

> 
> > Link: https://lore.kernel.org/all/ffd05070-9879-4468-94e3-b88968b4c21b@rock-chips.com/
> > Cc: stable@vger.kernel.org
> > Reported-by: Dragan Simic <dsimic@manjaro.org>
> > Reported-by: Shawn Lin <shawn.lin@rock-chips.com>
> > Reviewed-by: Dragan Simic <dsimic@manjaro.org>
> > Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com>
> > ---
> >  drivers/pci/controller/pcie-rockchip-host.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
> > index ee1822ca01db..4faf3e29b7d5 100644
> > --- a/drivers/pci/controller/pcie-rockchip-host.c
> > +++ b/drivers/pci/controller/pcie-rockchip-host.c
> > @@ -332,6 +332,10 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
> >  		/*
> >  		 * Enable retrain for gen2. This should be configured only after
> >  		 * gen1 finished.
> > +		 *
> > +		 * Dangerous and may lead to "catastrophic failure", with data loss
> > +		 * or worse!
> > +		 *
> 
> Wrap comment to fit in 80 columns like the rest of the file.
> 
> Remove spurious blank line at end.
> 
> This should probably be squashed with the first patch; I don't see the
> benefit of having them separate.
> 
> Why don't we just remove this whole "link_gen == 2" block?  If we
> don't want to use it, there's no point in keeping the code.

Yes, I think I'll go with this second option and remove the code
block outright.

Thanks,
Geraldo Nascimento

> 
> >  		 */
> >  		status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_CR + PCI_EXP_LNKCTL2);
> >  		status &= ~PCI_EXP_LNKCTL2_TLS;
> > -- 
> > 2.52.0
> > 
> > 
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