On Fri, 13 Mar 2020 at 03:23, Chen Qun <kuhn.chen...@huawei.com> wrote: > > The current code causes clang static code analyzer generate warning: > hw/net/imx_fec.c:858:9: warning: Value stored to 'value' is never read > value = value & 0x0000000f; > ^ ~~~~~~~~~~~~~~~~~~ > hw/net/imx_fec.c:864:9: warning: Value stored to 'value' is never read > value = value & 0x000000fd; > ^ ~~~~~~~~~~~~~~~~~~ > > According to the definition of the function, the two “value” assignments > should be written to registers. > > Reported-by: Euler Robot <euler.ro...@huawei.com> > Signed-off-by: Chen Qun <kuhn.chen...@huawei.com> > --- > Cc: Peter Maydell <peter.mayd...@linaro.org> > Cc: Jason Wang <jasow...@redhat.com> > Cc: Peter Chubb <peter.ch...@nicta.com.au> > > v1->v2: > The register 'ENET_TGSR' write-1-to-clear timer flag. > The register 'ENET_TCSRn' 7bit(TF) write-1-to-clear timer flag. > > v2->v3: > Optimize code style, based on discussions with Peter. > --- > hw/net/imx_fec.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/hw/net/imx_fec.c b/hw/net/imx_fec.c > index 6a124a154a..3547975710 100644 > --- a/hw/net/imx_fec.c > +++ b/hw/net/imx_fec.c > @@ -854,14 +854,17 @@ static void imx_enet_write(IMXFECState *s, uint32_t > index, uint32_t value) > s->regs[index] = value & 0x00007f7f; > break; > case ENET_TGSR: > - /* implement clear timer flag */ > - value = value & 0x0000000f; > + /* implement clear timer flag, 0-3 bits W1C, reserved bits write > zero */ > + s->regs[index] &= ~(value & 0x0000000f) & 0x0000000f;
I think I must have misunderstood what you were suggesting in your previous question. The final & with 0x0000000f here is unnecessary, because those bits are always 0 in s->regs[index] anyway. > break; > case ENET_TCSR0: > case ENET_TCSR1: > case ENET_TCSR2: > case ENET_TCSR3: > - value = value & 0x000000fd; > + /* 7 bits W1C, reserved bits write zero */ > + s->regs[index] &= ~(value & 0x00000080) & 0x000000ff; Similarly here. > + s->regs[index] &= ~0x0000007d; /* writable fields */ > + s->regs[index] |= (value & 0x0000007d); > break; > case ENET_TCCR0: > case ENET_TCCR1: Short answer: my recommendation is to use the expressions I recommended that you use... thanks -- PMM
