linux-kernel - [PATCH pci-next] PCI: dwc: put struct dw_pcie::{ep,pp} into a union to reduce its size

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Message-ID: <20210116152711.23411-1-alobakin@pm.me>
Date:   Sat, 16 Jan 2021 15:27:33 +0000
From:   Alexander Lobakin <alobakin@...me>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Rob Herring <robh@...nel.org>,
        Alexander Lobakin <alobakin@...me>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH pci-next] PCI: dwc: put struct dw_pcie::{ep,pp} into a union to reduce its size

A single dw_pcie entity can't be a root complex and an endpoint at
the same time.
We can use this to reduce the size of dw_pcie by 80, from 280 to 200
bytes (on x32, guess more on x64), by putting the related embedded
structures (struct pcie_port and struct dw_pcie_ep) into a union.

Signed-off-by: Alexander Lobakin <alobakin@...me>
---
 drivers/pci/controller/dwc/pcie-designware.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 5d979953800d..924ebeaa3885 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -265,8 +265,10 @@ struct dw_pcie {
 	size_t			atu_size;
 	u32			num_ib_windows;
 	u32			num_ob_windows;
-	struct pcie_port	pp;
-	struct dw_pcie_ep	ep;
+	union {
+		struct pcie_port	pp;
+		struct dw_pcie_ep	ep;
+	};
 	const struct dw_pcie_ops *ops;
 	unsigned int		version;
 	int			num_lanes;
-- 
2.30.0