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Date: Mon, 16 Apr 2018 15:37:57 +0100 From: Gustavo Pimentel <gustavo.pimentel@...opsys.com> To: bhelgaas@...gle.com, lorenzo.pieralisi@....com, Joao.Pinto@...opsys.com, jingoohan1@...il.com, kishon@...com, robh+dt@...nel.org, mark.rutland@....com Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, gustavo.pimentel@...opsys.com Subject: [PATCH v4 09/10] PCI: dwc: Small computation improvement Replaces a simple division by 2 to a right shift rotation of 1 bit. Probably any recent and decent compiler does this kind of substitution in order to improve code performance. Nevertheless it's a coding good practice whenever there is a division / multiplication by multiple of 2 to replace it by the equivalent operation in this case, the shift rotation. Signed-off-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com> --- Change v1->v2: - Nothing changed, just to follow the patch set version. Change v2->v3: - Nothing changed, just to follow the patch set version. Changes v3->v4: - Added a small explication to the log description. drivers/pci/dwc/pcie-designware-host.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c index 5a23f78..fc55fde 100644 --- a/drivers/pci/dwc/pcie-designware-host.c +++ b/drivers/pci/dwc/pcie-designware-host.c @@ -332,8 +332,8 @@ int dw_pcie_host_init(struct pcie_port *pp) cfg_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config"); if (cfg_res) { - pp->cfg0_size = resource_size(cfg_res) / 2; - pp->cfg1_size = resource_size(cfg_res) / 2; + pp->cfg0_size = resource_size(cfg_res) >> 1; + pp->cfg1_size = resource_size(cfg_res) >> 1; pp->cfg0_base = cfg_res->start; pp->cfg1_base = cfg_res->start + pp->cfg0_size; } else if (!pp->va_cfg0_base) { @@ -377,8 +377,8 @@ int dw_pcie_host_init(struct pcie_port *pp) break; case 0: pp->cfg = win->res; - pp->cfg0_size = resource_size(pp->cfg) / 2; - pp->cfg1_size = resource_size(pp->cfg) / 2; + pp->cfg0_size = resource_size(pp->cfg) >> 1; + pp->cfg1_size = resource_size(pp->cfg) >> 1; pp->cfg0_base = pp->cfg->start; pp->cfg1_base = pp->cfg->start + pp->cfg0_size; break; -- 2.7.4
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