Re: [PATCH] net: ethernet: ti: davinci_cpdma: fix fixed prio cpdma ctlr configuration

[Grygorii Strashko]

On 11/10/2016 01:52 PM, ivan.khoronzhuk wrote:
> On 10.11.16 18:37, Grygorii Strashko wrote:
> > On 11/09/2016 05:56 PM, Ivan Khoronzhuk wrote:
> > > On 09.11.16 23:09, Grygorii Strashko wrote:
> > > > On 11/08/2016 07:10 AM, Ivan Khoronzhuk wrote:
> > > > > The dma ctlr is reseted to 0 while cpdma start, thus cpdma ctlr
> > > >
> > > > I assume this is because cpdma_ctlr_start() does soft reset. Is it
> > > > correct?
> > > Probably not. I've seen this register doesn't hold any previous settings
> > > (just trash)
> >
> > What register CPDMA_DMACONTROL or CPSW_DMACTRL?
> >
> > > after cpdma_ctlr_stop(), actually after last channel is stopped (inside
> > > of cpdma_ctlr_stop()).
> >
> > So, You are stating that Registers context is changed after stop?
> >
> > > Then cpdma_ctlr_start() just reset it to 0.
> >
> > "just trash" or "0".
> >
> > Sry, I do not see how cpdma_ctlr_stop() can affect on registers state :(
> > and I'd very appreciated if can provide more detailed information.
> I've checked again, it was my mistake. It simply reset to 0 while soft
> reset.
>
> > > > > cannot be configured after cpdma is stopped. So, restore content
> > > > > of cpdma ctlr while off/on procedure.
> > > > >
> > > > > Based on net-next/master
> > > >
> > > > ^ remove it
> > > sure
> > >
> > > > > Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@xxxxxxxxxx>
> > > > > ---
> > > > >  drivers/net/ethernet/ti/cpsw.c          |   6 +-
> > > > >  drivers/net/ethernet/ti/davinci_cpdma.c | 103
> > > > > +++++++++++++++++---------------
> > > > >  drivers/net/ethernet/ti/davinci_cpdma.h |   2 +
> > > > >  3 files changed, 58 insertions(+), 53 deletions(-)
> > > > >
> > > > > diff --git a/drivers/net/ethernet/ti/cpsw.c
> > > > > b/drivers/net/ethernet/ti/cpsw.c
> > > > > index b1ddf89..4d04b8e 100644
> > > > > --- a/drivers/net/ethernet/ti/cpsw.c
> > > > > +++ b/drivers/net/ethernet/ti/cpsw.c
> > > > > @@ -1376,10 +1376,6 @@ static int cpsw_ndo_open(struct net_device
> > > > > *ndev)
> > > > >                    ALE_ALL_PORTS, ALE_ALL_PORTS, 0, 0);
> > > > >
> > > > >      if (!cpsw_common_res_usage_state(cpsw)) {
> > > > > -        /* setup tx dma to fixed prio and zero offset */
> > > > > -        cpdma_control_set(cpsw->dma, CPDMA_TX_PRIO_FIXED, 1);
> > > > > -        cpdma_control_set(cpsw->dma, CPDMA_RX_BUFFER_OFFSET, 0);
> > > > > -
> > > > >          /* disable priority elevation */
> > > > >          __raw_writel(0, &cpsw->regs->ptype);
> > > > >
> > > > > @@ -2710,6 +2706,8 @@ static int cpsw_probe(struct platform_device
> > > > > *pdev)
> > > > >      dma_params.desc_align        = 16;
> > > > >      dma_params.has_ext_regs        = true;
> > > > >      dma_params.desc_hw_addr         = dma_params.desc_mem_phys;
> > > > > +    dma_params.rxbuf_offset        = 0;
> > > > > +    dma_params.fixed_prio        = 1;
> > > >
> > > > Do we really need this new parameters? Do you have plans to use other
> > > > values?
> > > I'm ok if this is static (equally as a bunch of rest in dma_params), no
> > > see reason to use other values,
> >
> > That's what i wanted to know :) - go static, pls.
> >
> > > it at least now. But the issue is not only in these two parameters and
> > > not only in cpsw_ndo_open().
> > > It touches cpsw_set_channels() also, where ctlr stop/start is present.
> > > In order to not copy cpdma_control_set(cpsw->dma, CPDMA_TX_PRIO_FIXED,
> > > 1)...
> > > in all such kind places in eth drivers, better to allow the cpdma to
> > > control it's parameters...
> > >
> > > The cpdma ctlr register holds a little more parameters (but only two of
> > > them are set in cpsw)
> > > Maybe there is reason to save them also. Actually I'd seen this problem
> > > when playing with
> > > on/off channel shapers, unfortunately the cpdma ctlr holds this info
> > > also, and it was lost
> > > while on/off (but I'm going to restore it in chan_start()).
> >
> > I understand you change, but I'm note sure about real root cause :(
> so, are you Ok with current version?

No. pls, use constant values and do not introduce additional parameters.
Also, pls update commit message with new information.

--
regards,
-grygorii