linux-kernel - Re: [PATCH 4.19 058/118] PCI: designware-ep: Use aligned ATU window for raising MSI interrupts

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Message-ID: <20190616200056.GF6676@amd>
Date:   Sun, 16 Jun 2019 22:00:56 +0200
From:   Pavel Machek <pavel@...x.de>
To:     pavel@....cz
Cc:     linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 058/118] PCI: designware-ep: Use aligned ATU window
 for raising MSI interrupts

Hi!

> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index de8635af4cde..739d97080d3b 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -385,6 +385,7 @@ int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
>  {
>  	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>  	struct pci_epc *epc = ep->epc;
> +	unsigned int aligned_offset;
>  	u16 msg_ctrl, msg_data;
>  	u32 msg_addr_lower, msg_addr_upper, reg;
>  	u64 msg_addr;
> @@ -410,13 +411,15 @@ int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
>  		reg = ep->msi_cap + PCI_MSI_DATA_32;
>  		msg_data = dw_pcie_readw_dbi(pci, reg);
>  	}
> -	msg_addr = ((u64) msg_addr_upper) << 32 | msg_addr_lower;
> +	aligned_offset = msg_addr_lower & (epc->mem->page_size - 1);
> +	msg_addr = ((u64)msg_addr_upper) << 32 |
> +			(msg_addr_lower & ~aligned_offset);

This warks but is really... interesting code.

would (msg_addr_lower - aligned_offset) make more sense?

Thanks,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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