On Wednesday, April 11, 2018 3:40 AM, Gustavo Pimentel wrote:
>
> Hi Jingoo,
>
> On 11/04/2018 01:01, Jingoo Han wrote:
> > On Monday, April 9, 2018 5:41 AM, Gustavo Pimentel wrote:
> >>
> >> Replaces a simple division by 2 to a right shift rotation of 1 bit.
> >
> > It looks good. However, would you add a simple reason to the commit
> > message?
>
> Sure.
>
> Can be this one?
>
> 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.
Yes, that's what I wanted. The most platforms using 'dwc' are based on
ARM CPUs. So, the shift rotation can be better.
Thank you.
Best regards,
Jingoo Han
>
> >
> > Best regards,
> > Jingoo Han
> >
> >>
> >> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@xxxxxxxxxxxx>
> >> ---
> >> Change v1->v2:
> >> - 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 03e9b82..8e6fed4 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
> >>
> >
> >
>
> Regards,
> Gustavo
