[PATCH v2] PCI: imx6: Correct the epc_features of i.MX8M chips

[Hongxing Zhu]

> -----Original Message-----
> From: Bjorn Helgaas <helgaas at kernel.org>
> Sent: 2025年7月8日 23:48
> To: Hongxing Zhu <hongxing.zhu at nxp.com>
> Cc: mani at kernel.org; Frank Li <frank.li at nxp.com>; l.stach at pengutronix.de;
> lpieralisi at kernel.org; kwilczynski at kernel.org; robh at kernel.org;
> bhelgaas at google.com; shawnguo at kernel.org; s.hauer at pengutronix.de;
> kernel at pengutronix.de; festevam at gmail.com; linux-pci at vger.kernel.org;
> linux-arm-kernel at lists.infradead.org; imx at lists.linux.dev;
> linux-kernel at vger.kernel.org
> Subject: Re: [PATCH v2] PCI: imx6: Correct the epc_features of i.MX8M chips
> 
> On Tue, Jul 08, 2025 at 07:34:57AM +0000, Hongxing Zhu wrote:
> > > -----Original Message-----
> > > From: Bjorn Helgaas <helgaas at kernel.org>
> > ...
> > > On Tue, Jun 17, 2025 at 03:34:41PM +0800, Richard Zhu wrote:
> > > > i.MX8MQ PCIes have three 64-bit BAR0/2/4 capable and programmable
> > > > BARs.  But i.MX8MM and i.MX8MP PCIes only have
> > > > BAR0/BAR2 64bit programmable BARs, and one 256 bytes size fixed
> > > > BAR4.
> > > >
> > > > Correct the epc_features for i.MX8MM and i.MX8MP PCIes here.
> > > > i.MX8MQ is the same as i.MX8QXP, so set i.MX8MQ's epc_features to
> > > > imx8q_pcie_epc_features.
> > > >
> > > > Fixes: 75c2f26da03f ("PCI: imx6: Add i.MX PCIe EP mode support")
> > > > Signed-off-by: Richard Zhu <hongxing.zhu at nxp.com>
> > > > Reviewed-by: Frank Li <Frank.Li at nxp.com>
> > >
> > > "Correct the epc_features" doesn't include any specific information,
> > > and it's hard to extract the changes for a device from the commit
> > > log.
> > >
> > > This is really two fixes that should be separated so the commit logs
> > > can be specific:
> >
> > Yes, it's right.
> > Since it's just one line change for i.MX8MQ. So, I combine the changes
> > into this commit for i.MX8M chips.
> 
> I want to split them to make it easy for users to understand which changes are
> relevant to them.  E.g., I have an i.MX8MQ system; do I need this change and
> what does it mean for me?  Is it going to fix a problem I've been seeing?
Understood. Thanks for your comments.
Due to the ambiguous information, the previous epc_feature was wrongly
 defined.

Best Regards
Richard Zhu
> 
> > >   - For IMX8MQ_EP, use imx8q_pcie_epc_features (64-bit BARs 0, 2, 4)
> > >     instead of imx8m_pcie_epc_features (64-bit BARs 0, 2).
> > >
> > >   - For IMX8MM_EP and IMX8MP_EP, add fixed 256-byte BAR 4 in
> > >     imx8m_pcie_epc_features.