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Date: Tue, 24 Apr 2018 14:05:26 +0000
From: Alan Douglas <adouglas@...ence.com>
To: Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
Kishon Vijay Abraham I <kishon@...com>,
"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
"lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
"Joao.Pinto@...opsys.com" <Joao.Pinto@...opsys.com>,
"jingoohan1@...il.com" <jingoohan1@...il.com>,
"niklas.cassel@...s.com" <niklas.cassel@...s.com>,
"jesper.nilsson@...s.com" <jesper.nilsson@...s.com>
CC: "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [RFC 01/10] PCI: dwc: Add MSI-X callbacks handler
Hi Kishon,
On 24 April 2018 10:36 Gustavo Pimentel wrote:
> Hi Kishon,
>
> On 24/04/2018 08:07, Kishon Vijay Abraham I wrote:
> > Hi,
> >
> > On Monday 23 April 2018 03:06 PM, Gustavo Pimentel wrote:
> >> Hi Kishon,
> >>
> >> On 16/04/2018 10:29, Kishon Vijay Abraham I wrote:
> >>> Hi Gustavo,
> >>>
> >>> On Tuesday 10 April 2018 10:44 PM, Gustavo Pimentel wrote:
> >>>> Changes the pcie_raise_irq function signature, namely the
> >>>> interrupt_num variable type from u8 to u16 to accommodate the MSI-X
> >>>> maximum interrupts of 2048.
> >>>>
> >>>> Implements a PCIe config space capability iterator function to
> >>>> search and save the MSI and MSI-X pointers. With this method the
> >>>> code becomes more generic and flexible.
> >>>>
> >>>> Implements MSI-X set/get functions for sysfs interface in order to
> >>>> change the EP entries number.
> >>>>
> >>>> Implements EP MSI-X interface for triggering interruptions.
> >>>>
> >>>> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com>
> >>>> ---
> >>>> drivers/pci/dwc/pci-dra7xx.c | 2 +-
> >>>> drivers/pci/dwc/pcie-artpec6.c | 2 +-
> >>>> drivers/pci/dwc/pcie-designware-ep.c | 145
> ++++++++++++++++++++++++++++++++-
> >>>> drivers/pci/dwc/pcie-designware-plat.c | 6 +-
> >>>> drivers/pci/dwc/pcie-designware.h | 23 +++++-
> >>>> 5 files changed, 173 insertions(+), 5 deletions(-)
> >>>>
> >>>> diff --git a/drivers/pci/dwc/pci-dra7xx.c
> >>>> b/drivers/pci/dwc/pci-dra7xx.c index ed8558d..5265725 100644
> >>>> --- a/drivers/pci/dwc/pci-dra7xx.c
> >>>> +++ b/drivers/pci/dwc/pci-dra7xx.c
> >>>> @@ -369,7 +369,7 @@ static void dra7xx_pcie_raise_msi_irq(struct
> >>>> dra7xx_pcie *dra7xx, }
> >>>>
> >>>> static int dra7xx_pcie_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
> >>>> - enum pci_epc_irq_type type, u8
> interrupt_num)
> >>>> + enum pci_epc_irq_type type, u16
> interrupt_num)
> >>>> {
> >>>> struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> >>>> struct dra7xx_pcie *dra7xx = to_dra7xx_pcie(pci); diff --git
> >>>> a/drivers/pci/dwc/pcie-artpec6.c b/drivers/pci/dwc/pcie-artpec6.c
> >>>> index e66cede..96dc259 100644
> >>>> --- a/drivers/pci/dwc/pcie-artpec6.c
> >>>> +++ b/drivers/pci/dwc/pcie-artpec6.c
> >>>> @@ -428,7 +428,7 @@ static void artpec6_pcie_ep_init(struct
> >>>> dw_pcie_ep *ep) }
> >>>>
> >>>> static int artpec6_pcie_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
> >>>> - enum pci_epc_irq_type type, u8
> interrupt_num)
> >>>> + enum pci_epc_irq_type type, u16
> interrupt_num)
> >>>> {
> >>>> struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> >>>>
> >>>> diff --git a/drivers/pci/dwc/pcie-designware-ep.c
> >>>> b/drivers/pci/dwc/pcie-designware-ep.c
> >>>> index 15b22a6..874d4c2 100644
> >>>> --- a/drivers/pci/dwc/pcie-designware-ep.c
> >>>> +++ b/drivers/pci/dwc/pcie-designware-ep.c
> >>>> @@ -40,6 +40,44 @@ void dw_pcie_ep_reset_bar(struct dw_pcie
> *pci, enum pci_barno bar)
> >>>> __dw_pcie_ep_reset_bar(pci, bar, 0); }
> >>>>
> >>>> +void dw_pcie_ep_find_cap_addr(struct dw_pcie_ep *ep) {
> >>>
> >>> This should be implemented in a generic way similar to
> pci_find_capability().
> >>> It'll be useful when we try to implement other capabilities as well.
> >>
> >> Hum, what you suggest? Something implemented on the pci-epf-core?
> >
> > yeah, Initially thought it could be implemented as a helper function
> > in pci-epc-core so that both designware and cadence can use it.
>
> That would be nice, however I couldn't find out how to access the config
> space, through the pci_epf or pci_epc structs.
>
> So, I reworked the functions like this:
>
> (on pcie-designware-ep.c)
>
> u8 __dw_pcie_ep_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_ep_find_next_cap(pci, next_cap_ptr, cap); }
>
> u8 dw_pcie_ep_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_ep_find_next_cap(pci, next_cap_ptr, cap); }
>
> int dw_pcie_ep_init(struct dw_pcie_ep *ep) { [...]
> ep->msi_cap = dw_pcie_ep_find_capability(pci, PCI_CAP_ID_MSI);
> ep->msix_cap = dw_pcie_ep_find_capability(pci, PCI_CAP_ID_MSIX); [...]
> }
>
> >
> > But do we really have to find the address like this? since all
> > designware IP's will have a particular capability at a fixed address
> > offset, why not follow use existing mechanism in dw_pcie_ep_get_msi?
>
> The capabilities are not fixed to a specific address offset by default they
> assume those values, but they can be easily change at design stage.
>
> >
> > Or is it possible for a particular capability to have address offsets
> > for different vendors? How is it for cadence?
>
> Yes, it's possible to have different address offset for different vendors.
>
For cadence the offsets are fixed for each specific hw (if a capability is
disabled it will just be removed from the linked list) but it would be
better to allow for the possibility for them to vary between different hw.
> >
> > Thanks
> > Kishon
> >
>
> Thanks,
> Gustavo
Regards,
Alan
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