Hi Sergei,
> Subject: RE: [RFC/PATCH 06/18] ravb: Add multi_tsrq to struct ravb_hw_info
>
> Hi Sergei,
>
> Thanks for the feedback.
>
> > Subject: Re: [RFC/PATCH 06/18] ravb: Add multi_tsrq to struct
> > ravb_hw_info
> >
> > On 9/23/21 5:08 PM, Biju Das wrote:
> >
> > > R-Car AVB-DMAC has 4 Transmit start Request queues, whereas RZ/G2L
> > > has only 1 Transmit start Request queue(Best Effort)
> > >
> > > Add a multi_tsrq hw feature bit to struct ravb_hw_info to enable
> > > this only for R-Car. This will allow us to add single TSRQ support
> > > for RZ/G2L.
> > >
> > > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > ---
> > > drivers/net/ethernet/renesas/ravb.h | 1 +
> > > drivers/net/ethernet/renesas/ravb_main.c | 12 ++++++++++--
> > > 2 files changed, 11 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/renesas/ravb.h
> > > b/drivers/net/ethernet/renesas/ravb.h
> > > index bb92469d770e..c043ee555be4 100644
> > > --- a/drivers/net/ethernet/renesas/ravb.h
> > > +++ b/drivers/net/ethernet/renesas/ravb.h
> > > @@ -1006,6 +1006,7 @@ struct ravb_hw_info {
> > > unsigned multi_irqs:1; /* AVB-DMAC and E-MAC has multiple
> > irqs */
> > > unsigned no_gptp:1; /* AVB-DMAC does not support gPTP
> > feature */
> > > unsigned ccc_gac:1; /* AVB-DMAC has gPTP support active in
> > config mode */
> > > + unsigned multi_tsrq:1; /* AVB-DMAC has MULTI TSRQ */
> >
> > Maybe 'single_tx_q' instead?
>
> Since it is called transmit start request queue, it is better to be named
> as single_tsrq to match with hardware manual and I will update the comment
> with "GbEthernet DMAC has single TSRQ"
> Please let me know are you ok with it. Other wise I would like to use
> existing name.
On the next revision as you proposed for [1],
I will use a u32 tsrq, instead of bit, there by we can avoid a check.
https://patchwork.kernel.org/project/linux-renesas-soc/patch/20210923140813.13541-12-biju.das.jz@xxxxxxxxxxxxxx/
>
> >
> > > };
> > >
> > > struct ravb_private {
> > > diff --git a/drivers/net/ethernet/renesas/ravb_main.c
> > > b/drivers/net/ethernet/renesas/ravb_main.c
> > > index 8663d83507a0..d37d73f6d984 100644
> > > --- a/drivers/net/ethernet/renesas/ravb_main.c
> > > +++ b/drivers/net/ethernet/renesas/ravb_main.c
> > > @@ -776,11 +776,17 @@ static void ravb_rcv_snd_enable(struct
> > > net_device *ndev)
> > > /* function for waiting dma process finished */ static int
> > > ravb_stop_dma(struct net_device *ndev) {
> > > + struct ravb_private *priv = netdev_priv(ndev);
> > > + const struct ravb_hw_info *info = priv->info;
> > > int error;
> > >
> > > /* Wait for stopping the hardware TX process */
> > > - error = ravb_wait(ndev, TCCR,
> > > - TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 | TCCR_TSRQ3, 0);
> > > + if (info->multi_tsrq)
> > > + error = ravb_wait(ndev, TCCR,
> > > + TCCR_TSRQ0 | TCCR_TSRQ1 | TCCR_TSRQ2 |
> > TCCR_TSRQ3, 0);
> > > + else
> > > + error = ravb_wait(ndev, TCCR, TCCR_TSRQ0, 0);
> >
> > Aren't the TSRQ1/2/3 bits reserved on RZ/G2L? If so, this new flag
> > adds a little value, I think... unless you plan to use this flag
> > further in the series?
>
> It will be confusing for RZ/G2L users. HW manual does not describes
> TSRQ1/2/3 and we are writing undocumented registers which is reserved.
>
> Tomorrow it can happen that this reserved bits(90% it will not happen)
> will be used for describing something else.
>
> It is unsafe to use reserved bits. Are you agreeing with this?
As per the above discussion, we can replace the above check as you proposed for [1]
error = ravb_wait(ndev, TCCR, info->tsrq, 0);
[1] https://patchwork.kernel.org/project/linux-renesas-soc/patch/20210923140813.13541-12-biju.das.jz@xxxxxxxxxxxxxx/
regards,
Biju
