linux-kernel - Re: [PATCH v3 5/7] PCI: brcmstb: add MSI capability

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Date:   Mon, 02 Dec 2019 10:59:36 +0100
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Andrew Murray <andrew.murray@....com>
Cc:     maz@...nel.org, linux-kernel@...r.kernel.org,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Eric Anholt <eric@...olt.net>,
        Stefan Wahren <wahrenst@....net>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list@...adcom.com, james.quinlan@...adcom.com,
        mbrugger@...e.com, phil@...pberrypi.org, jeremy.linton@....com,
        linux-pci@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 5/7] PCI: brcmstb: add MSI capability

Hi Andrew,

On Fri, 2019-11-29 at 15:46 +0000, Andrew Murray wrote:
> On Tue, Nov 26, 2019 at 10:19:43AM +0100, Nicolas Saenz Julienne wrote:
> > From: Jim Quinlan <james.quinlan@...adcom.com>
> > 
> > This adds MSI support to the Broadcom STB PCIe host controller. The MSI
> > controller is physically located within the PCIe block, however, there
> > is no reason why the MSI controller could not be moved elsewhere in the
> > future. MSIX is not supported by the HW.
> > 
> > Since the internal Brcmstb MSI controller is intertwined with the PCIe
> > controller, it is not its own platform device but rather part of the
> > PCIe platform device.
> > 
> > Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
> > Co-developed-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> > Reviewed-by: Marc Zyngier <maz@...nel.org>
> > 
> > ---
> > 
> > Changes since v2 (kept Marc's Reviewed-by as changes didn't affect irq
> > subsystem stuff or seem petty enough):
> >   - Use standard APIs on register operations
> >   - Get rid of revision code
> 
> Do any RPI4's have a HW revision of less than 33?

No, IIRC it's actually revision 34. I had left that bit of code in, following
the same train of thought as with the of_data on the device-tree part of the
driver: "It's harmless and should make accomodating other devices easier." It
turned out not to be such a great approach. Lesson's learned. So I decided to
remove it.

> >   - Update rules to msi_target_addr selection
> >   - Remove unwarranted MSI_FLAG_PCI_MSIX
> >   - Small cosmetic changes
> > 
> > Changes since v1:cuando tenías tu vacaciones?
> >   - Move revision code and some registers to this patch
> >   - Use PCIE_MSI_IRQ_DOMAIN in Kconfig
> >   - Remove redundant register read from ISR
> >   - Fail probe on MSI init error
> >   - Get rid of msi_internal
> >   - Use bitmap family of functions
> >   - Use edge triggered setup
> >   - Add comment regarding MultiMSI
> >   - Simplify compose_msi_msg to avoid reg read
> > 
> > This is based on Jim's original submission[1] with some slight changes
> > regarding how pcie->msi_target_addr is decided.
> > 
> > [1] https://patchwork.kernel.org/patch/10605955/
> > 
> >  drivers/pci/controller/Kconfig        |   1 +
> >  drivers/pci/controller/pcie-brcmstb.c | 261 +++++++++++++++++++++++++-
> >  2 files changed, 261 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
> > index 27504f108ee5..918e283bbff1 100644
> > +
> > +static void brcm_msi_compose_msi_msg(struct irq_data *data, struct msi_msg
> > *msg)
> > +{
> > +	struct brcm_msi *msi = irq_data_get_irq_chip_data(data);
> > +
> > +	msg->address_lo = lower_32_bits(msi->target_addr);
> > +	msg->address_hi = upper_32_bits(msi->target_addr);
> > +	msg->data = 0x6540 | data->hwirq;
> 
> NIT: Perhaps this 0x6540 can be a define - just in the same way we have a
> define
> for PCIE_MISC_MSI_DATA_CONFIG_VAL.

Noted

Regards,
Nicolas


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