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    SubjectRe: [PATCH 11/30] usb: dwc2: gadget: Avoid pointless read of EP control register
    On Thu, Jul 02, 2020 at 03:46:06PM +0100, Lee Jones wrote:
    > Commit ec1f9d9f01384 ("usb: dwc2: gadget: parity fix in isochronous mode") moved
    > these checks to dwc2_hsotg_change_ep_iso_parity() back in 2015. The assigned
    > value hasn't been read back since. Let's remove the unnecessary H/W read.
    >
    > Fixes the following W=1 warning:
    >
    > drivers/usb/dwc2/gadget.c: In function ‘dwc2_hsotg_epint’:
    > drivers/usb/dwc2/gadget.c:2981:6: warning: variable ‘ctrl’ set but not used [-Wunused-but-set-variable]
    > 2981 | u32 ctrl;
    > | ^~~~
    >
    > Cc: Minas Harutyunyan <hminas@synopsys.com>
    > Cc: Ben Dooks <ben@simtec.co.uk>
    > Signed-off-by: Lee Jones <lee.jones@linaro.org>
    > ---
    > drivers/usb/dwc2/gadget.c | 2 --
    > 1 file changed, 2 deletions(-)
    >
    > diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
    > index 116e6175c7a48..fa07e3fcb8841 100644
    > --- a/drivers/usb/dwc2/gadget.c
    > +++ b/drivers/usb/dwc2/gadget.c
    > @@ -2975,10 +2975,8 @@ static void dwc2_hsotg_epint(struct dwc2_hsotg *hsotg, unsigned int idx,
    > u32 epctl_reg = dir_in ? DIEPCTL(idx) : DOEPCTL(idx);
    > u32 epsiz_reg = dir_in ? DIEPTSIZ(idx) : DOEPTSIZ(idx);
    > u32 ints;
    > - u32 ctrl;
    >
    > ints = dwc2_gadget_read_ep_interrupts(hsotg, idx, dir_in);
    > - ctrl = dwc2_readl(hsotg, epctl_reg);

    As you know, lots of hardware requires reads to happen to do things, so
    are you sure it is safe to remove this read call?

    thanks,

    greg k-h

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