Re: [Qemu-devel] [PATCH v3] e1000: clean up phyreg_writeops/set_phy_ctrl

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jul 01, 2014 at 03:03:48PM -0400, Gabriel L. Somlo wrote:
> Make phyreg_writeops responsible for actually writing their
> respective phy registers. The only current instance of
> phyreg_writeops is set_phy_ctrl(), which we modify to actually
> write the register, while also correctly handling reserved and
> self-clearing bits.
> 
> have_autoneg() does not need to check for MII_CR_RESTART_AUTO_NEG,
> since the only time the flag comes into play is during set_phy_ctrl(),
> and never actually gets written to the phy control register. We also
> move it in front of set_phy_ctrl(), to avoid a forward declaration.
> 
> Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
> ---


Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Applied, thanks!

> Michael, Stefan:
> 
> Here's a new version of this patch with slightly better (IMHO) formatting.
> I think the merits are 1. handling bits which are reserved or self
> clearing; and 2. eliminating the surprise of a "write op" that does not
> actually write to its register :)
> 
> Regarding the "sibling" patch originally accompanying this one (which
> increased the timer delay for autonegotiation), I'll take a while
> longer to figure out what's really going on, so I'll send out a separate
> patch if/when that happens.
> 
> Please apply (or review/critique) this one independently.
> 
> Thanks,
>   Gabriel
> 
>  hw/net/e1000.c | 31 +++++++++++++++++--------------
>  1 file changed, 17 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/net/e1000.c b/hw/net/e1000.c
> index 0fc29a0..04c0f91 100644
> --- a/hw/net/e1000.c
> +++ b/hw/net/e1000.c
> @@ -186,21 +186,31 @@ e1000_link_up(E1000State *s)
>      s->phy_reg[PHY_STATUS] |= MII_SR_LINK_STATUS;
>  }
>  
> +static bool
> +have_autoneg(E1000State *s)
> +{
> +    return (s->compat_flags & E1000_FLAG_AUTONEG) &&
> +           (s->phy_reg[PHY_CTRL] & MII_CR_AUTO_NEG_EN);
> +}
> +
>  static void
>  set_phy_ctrl(E1000State *s, int index, uint16_t val)
>  {
> +    /* bits 0-5 reserved; MII_CR_[RESTART_AUTO_NEG,RESET] are self clearing */
> +    s->phy_reg[PHY_CTRL] = val & ~(0x3f |
> +                                   MII_CR_RESET |
> +                                   MII_CR_RESTART_AUTO_NEG);
> +
>      /*
>       * QEMU 1.3 does not support link auto-negotiation emulation, so if we
>       * migrate during auto negotiation, after migration the link will be
>       * down.
>       */
> -    if (!(s->compat_flags & E1000_FLAG_AUTONEG)) {
> -        return;
> -    }
> -    if ((val & MII_CR_AUTO_NEG_EN) && (val & MII_CR_RESTART_AUTO_NEG)) {
> +    if (have_autoneg(s) && (val & MII_CR_RESTART_AUTO_NEG)) {
>          e1000_link_down(s);
>          DBGOUT(PHY, "Start link auto negotiation\n");
> -        timer_mod(s->autoneg_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 500);
> +        timer_mod(s->autoneg_timer,
> +                  qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 500);
>      }
>  }
>  
> @@ -446,8 +456,9 @@ set_mdic(E1000State *s, int index, uint32_t val)
>          } else {
>              if (addr < NPHYWRITEOPS && phyreg_writeops[addr]) {
>                  phyreg_writeops[addr](s, index, data);
> +            } else {
> +                s->phy_reg[addr] = data;
>              }
> -            s->phy_reg[addr] = data;
>          }
>      }
>      s->mac_reg[MDIC] = val | E1000_MDIC_READY;
> @@ -848,14 +859,6 @@ receive_filter(E1000State *s, const uint8_t *buf, int size)
>      return 0;
>  }
>  
> -static bool
> -have_autoneg(E1000State *s)
> -{
> -    return (s->compat_flags & E1000_FLAG_AUTONEG) &&
> -           (s->phy_reg[PHY_CTRL] & MII_CR_AUTO_NEG_EN) &&
> -           (s->phy_reg[PHY_CTRL] & MII_CR_RESTART_AUTO_NEG);
> -}
> -
>  static void
>  e1000_set_link_status(NetClientState *nc)
>  {
> -- 
> 1.9.3