Re: [PATCH V4 05/16] PCI: dwc: Move config space capability search API

[Vidya Sagar]

On 4/24/2019 2:02 AM, Bjorn Helgaas wrote:
> On Tue, Apr 23, 2019 at 01:57:19PM +0530, Vidya Sagar wrote:
> > Move PCIe config space capability search API to common DesignWare file
> > as this can be used by both host and ep mode codes.
> >
> > Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
> > Acked-by: Gustavo Pimentel <gustavo.pimentel@xxxxxxxxxxxx>
> > ---
> > Changes from [v3]:
> > * Rebased to linux-next top of the tree
> >
> > Changes from [v2]:
> > * None
> >
> > Changes from [v1]:
> > * Removed dw_pcie_find_next_ext_capability() API from here and made a
> >    separate patch for that
> >
> >   drivers/pci/controller/dwc/pcie-designware.c | 33 ++++++++++++++++++++
> >   drivers/pci/controller/dwc/pcie-designware.h |  2 ++
>
> You claim this is a "move", but I only see adds.  Where did it move
> *from*?
These are supposed to be moved from pcie-designware-ep.c file. That was the case
with my old patches but when I rebased them onto ToT, I missed the change that
removes them from pcie-designware-ep.c file. Thanks for catching this. I'll
address it in the next patch.

> While you're at it, can you add a comment in the code about why we
> can't use the regular pci_find_capability() interface?  It's really a
> shame to have to reimplement that.
Regular pci_find_capability() uses 'struct pci_dev *dev' pointer and can be used
only after device enumeration is done. Whereas, these APIs are used particularly
before link up and use 'struct dw_pcie *pci' pointer.

> >   2 files changed, 35 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 8e0081ccf83b..6a98135244d6 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -20,6 +20,39 @@
> >   #define PCIE_PHY_DEBUG_R1_LINK_UP	(0x1 << 4)
> >   #define PCIE_PHY_DEBUG_R1_LINK_IN_TRAINING	(0x1 << 29)
> >   
> > +static u8 __dw_pcie_find_next_cap(struct dw_pcie *pci, u8 cap_ptr,
> > +				  u8 cap)
> > +{
> > +	u8 cap_id, next_cap_ptr;
> > +	u16 reg;
> > +
> > +	reg = dw_pcie_readw_dbi(pci, cap_ptr);
> > +	next_cap_ptr = (reg & 0xff00) >> 8;
> > +	cap_id = (reg & 0x00ff);
> > +
> > +	if (!next_cap_ptr || cap_id > PCI_CAP_ID_MAX)
> > +		return 0;
> > +
> > +	if (cap_id == cap)
> > +		return cap_ptr;
> > +
> > +	return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
> > +}
> > +
> > +u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
> > +{
> > +	u8 next_cap_ptr;
> > +	u16 reg;
> > +
> > +	reg = dw_pcie_readw_dbi(pci, PCI_CAPABILITY_LIST);
> > +	next_cap_ptr = (reg & 0x00ff);
> > +
> > +	if (!next_cap_ptr)
> > +		return 0;
> > +
> > +	return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
> > +}
> > +
> >   int dw_pcie_read(void __iomem *addr, int size, u32 *val)
> >   {
> >   	if (!IS_ALIGNED((uintptr_t)addr, size)) {
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index 9ee98ced1ef6..35160b4ce929 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -248,6 +248,8 @@ struct dw_pcie {
> >   #define to_dw_pcie_from_ep(endpoint)   \
> >   		container_of((endpoint), struct dw_pcie, ep)
> >   
> > +u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap);
> > +
> >   int dw_pcie_read(void __iomem *addr, int size, u32 *val);
> >   int dw_pcie_write(void __iomem *addr, int size, u32 val);
> >   
> > --
> > 2.17.1