netdev - Re: [PATCH v3 1/4] net: nb8800: Drop generic support

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Message-ID: <yw1x60ad2fyz.fsf@mansr.com>
Date:   Tue, 14 Nov 2017 12:37:56 +0000
From:   Måns Rullgård <mans@...sr.com>
To:     Marc Gonzalez <marc_gonzalez@...madesigns.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Thibaud Cornic <thibaud_cornic@...madesigns.com>,
        Mason <slash.tmp@...e.fr>
Subject: Re: [PATCH v3 1/4] net: nb8800: Drop generic support

Marc Gonzalez <marc_gonzalez@...madesigns.com> writes:

> According to our HW dev, there is no provision for software to safely
> disable RX DMA in the AU-NB8800 hardware block (ethernet DMA). Thus,
> it is the responsibility of the SoC designer to provide such a feature.
>
> The nb8800_dma_stop() implementation is a clever hack that works most
> of the times, but it breaks the DMA state machine in rare cases.
>
> Therefore, let's drop generic support.
>
> FWIW, tango chips provide a reset register. When the ethernet block
> comes out of reset, DMA is disabled.
>
> Signed-off-by: Marc Gonzalez <marc_gonzalez@...madesigns.com>
> ---
>  drivers/net/ethernet/aurora/nb8800.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/aurora/nb8800.c b/drivers/net/ethernet/aurora/nb8800.c
> index e94159507847..26f719e2d6ca 100644
> --- a/drivers/net/ethernet/aurora/nb8800.c
> +++ b/drivers/net/ethernet/aurora/nb8800.c
> @@ -1335,9 +1335,6 @@ static const struct nb8800_ops nb8800_tango4_ops = {
>  };
>
>  static const struct of_device_id nb8800_dt_ids[] = {
> -	{
> -		.compatible = "aurora,nb8800",
> -	},
>  	{
>  		.compatible = "sigma,smp8642-ethernet",
>  		.data = &nb8800_tangox_ops,
> -- 

Please leave this.  It works just fine on tango3.

-- 
Måns Rullgård