linux-kernel - Re: [PATCH net-next v2 3/3] net: stmmac: Configure AXI on Tegra234 MGBE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date: Tue, 13 Feb 2024 16:51:34 +0100
From: "Thierry Reding" <thierry.reding@...il.com>
To: "Serge Semin" <fancer.lancer@...il.com>
Cc: "Alexandre Torgue" <alexandre.torgue@...s.st.com>, "Jose Abreu"
 <joabreu@...opsys.com>, "David S. Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, "Jakub Kicinski" <kuba@...nel.org>, "Paolo
 Abeni" <pabeni@...hat.com>, <netdev@...r.kernel.org>,
 <linux-stm32@...md-mailman.stormreply.com>,
 <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
 <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH net-next v2 3/3] net: stmmac: Configure AXI on Tegra234
 MGBE

On Mon Feb 5, 2024 at 1:44 AM CET, Serge Semin wrote:
> On Fri, Feb 02, 2024 at 12:53:35PM +0100, Thierry Reding wrote:
> > From: Thierry Reding <treding@...dia.com>
> > 
> > Allow the device to use bursts and increase the maximum number of
> > outstanding requests to improve performance. Measurements show an
> > increase in throughput of around 5x on a 1 Gbps link.
> > 
> > Signed-off-by: Thierry Reding <treding@...dia.com>
> > ---
> >  drivers/net/ethernet/stmicro/stmmac/dwmac-tegra.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-tegra.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-tegra.c
> > index bab57d1675df..b6bfa48f279d 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-tegra.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-tegra.c
> > @@ -199,6 +199,12 @@ static void mgbe_uphy_lane_bringup_serdes_down(struct net_device *ndev, void *mg
> >  	writel(value, mgbe->xpcs + XPCS_WRAP_UPHY_RX_CONTROL);
> >  }
> >  
> > +static const struct stmmac_axi tegra234_mgbe_axi = {
> > +	.axi_wr_osr_lmt = 63,
> > +	.axi_rd_osr_lmt = 63,
> > +	.axi_blen = { 256, },
> > +};
> > +
> >  static int tegra_mgbe_probe(struct platform_device *pdev)
> >  {
> >  	struct plat_stmmacenet_data *plat;
> > @@ -284,6 +290,9 @@ static int tegra_mgbe_probe(struct platform_device *pdev)
> >  	if (err < 0)
> >  		goto disable_clks;
> >  
> > +	/* setup default AXI configuration */
> > +	res.axi = &tegra234_mgbe_axi;
> > +
> >  	plat = devm_stmmac_probe_config_dt(pdev, &res);
> >  	if (IS_ERR(plat)) {
> >  		err = PTR_ERR(plat);
>
> The entire series can be converted to just a few lines of change:

Sorry for the delay, I missed this reply.

>  	plat = devm_stmmac_probe_config_dt(pdev, res.mac);
>  	if (IS_ERR(plat)) {
>  		err = PTR_ERR(plat);
>  		goto disable_clks;
>  	}
> +
> +	if (IS_ERR_OR_NULL(plat->axi)) {
> +		plat->axi = devm_kzalloc(&pdev->dev, sizeof(*axi), GFP_KERNEL);
> +		if (!plat->axi) {
> +			ret = -ENOMEM;
> +			goto disable_clks;
> +		}
> +	} /* else memset plat->axi with zeros if you wish */
> +
> +	plat->axi->axi_wr_osr_lmt = 63;
> +	plat->axi->axi_rd_osr_lmt = 63;
> +	plat->axi->axi_blen[0] = 256;
>  
>  	plat->has_xgmac = 1;
>  	plat->flags |= STMMAC_FLAG_TSO_EN;
>  	plat->pmt = 1;
>
> Please don't overcomplicate the already overcomplicated driver with a
> functionality which can be reached by the default one. In this case
> the easiest way is to let the generic code work and then
> override/replace/fix/etc the retrieved values. Thus there won't be
> need in adding the redundant functionality and keep the generic
> DT-platform code a bit simpler to read.

I'm not sure I understand how this is overcomplicating things. The code
is pretty much unchanged, except that the AXI configuration can now have
driver-specified defaults before the DT is parsed. Perhaps I need to add
comments to make that a bit clearer?

While your version is certainly simpler it has the drawback that it no
longer allows the platform defaults to be overridden in device tree. I
would prefer if the defaults can be derived from the compatible string
but if need be for those defaults to still be overridable from device
tree.

Thierry

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)