lkml.org 
[lkml]   [2018]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v5 09/10] PCI: dwc: Small computation improvement
Date
On Tuesday, April 17, 2018 10:34 AM, Gustavo Pimentel wrote:
>
> 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@synopsys.com>

Acked-by: Jingoo Han <jingoohan1@gmail.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.
> Changes v4->v5:
> - Nothing changed, just to follow the patch set version.
>
> 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
>


\
 
 \ /
  Last update: 2018-04-17 16:38    [W:0.110 / U:0.036 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site