Date: Mon, 13 May 2024 17:04:56 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: Yanteng Si <siyanteng@...ngson.cn>, chenhuacai@...nel.org
Cc: andrew@...n.ch, hkallweit1@...il.com, peppe.cavallaro@...com, 
	alexandre.torgue@...s.st.com, joabreu@...opsys.com, Jose.Abreu@...opsys.com, 
	linux@...linux.org.uk, guyinggang@...ngson.cn, netdev@...r.kernel.org, 
	chris.chenfeiyang@...il.com, siyanteng01@...il.com
Subject: Re: [PATCH net-next v12 06/15] net: stmmac: dwmac-loongson: Split up
 the platform data initialization

On Mon, May 13, 2024 at 07:07:38PM +0800, Yanteng Si wrote:
> 
> 在 2024/5/4 02:08, Serge Semin 写道:
> > > [PATCH net-next v12 06/15] net: stmmac: dwmac-loongson: Split up the platform data initialization
> > Please convert the subject to being more specific, like this:
> > 
> > net: stmmac: dwmac-loongson: Detach GMAC-specific platform data init
> > 
> > On Thu, Apr 25, 2024 at 09:04:37PM +0800, Yanteng Si wrote:
> > > Based on IP core classification, loongson has two types of network
> > What is the real company name? At least start the name with the
> > capital letter.
> > * everywhere
> OK,  LOONGSON
> > 
> > > devices: GMAC and GNET. GMAC's ip_core id is 0x35/0x37, while GNET's
> > > ip_core id is 0x37/0x10.
> > s/ip_core/IP-core
> > 
> > Once again the IP-core ID isn't _hex_, but a number of the format:
> > "v+Major.Minor"
> > so use the _real_ IP-core version number everywhere. Note mentioning
> > that some of your GNET device has the GMAC_VERSION.SNPSVER hardwired
> > to 0x10 is completely redundant in this and many other context. The
> > only place where it's relevant is the patch(es) where you have the
> > Snps ID override.
> OK.
> > 
> > > Device tables:
> > > 
> > > device    type    pci_id    snps_id    channel
> > > ls2k1000  gmac    7a03      0x35/0x37   1
> > > ls7a1000  gmac    7a03      0x35/0x37   1
> > > ls2k2000  gnet    7a13      0x10        8
> > > ls7a2000  gnet    7a13      0x37        1
> > s/gmac/GMAC
> > s/gnet/GNET
> > s/pci_id/PCI Dev ID
> > s/snsp_id/Synopys Version
> > s/channels/DMA-channels
> > s/ls2k/LS2K
> > s/ls7a/LS7A
> > 
> > * everywhere
> OK.
> > 
> > > The GMAC device only has a MAC chip inside and needs an
> > > external PHY chip;
> > > 
> > > To later distinguish 8-channel gnet devices from single-channel
> > > gnet/gmac devices, move rx_queues_to_use loongson_default_data
> > > to loongson_dwmac_probe(). Also move mac_interface to
> > > loongson_default_data().
> > Again. This is only a part of the reason why you need this change.
> > The main reason is to provide the two-leveled platform data init
> > functions: fist one is the common method initializing the data common
> > for both GMAC and GNET, second one is the device-specific data
> > initializer.
> > 
> > To sum up I would change the commit log to something like this:
> > 
> > "Loongson delivers two types of the network devices: Loongson GMAC and
> > Loongson GNET in the framework of four CPU/Chipsets revisions:
> > 
> >     Chip             Network  PCI Dev ID   Synopys Version   DMA-channel
> > LS2K1000 CPU         GMAC      0x7a03       v3.50a/v3.73a        1
> > LS7A1000 Chipset     GMAC      0x7a03       v3.50a/v3.73a        1
> > LS2K2000 CPU         GNET      0x7a13          v3.73a            8
> > LS7A2000 Chipset     GNET      0x7a13          v3.73a            1
> > 
> > The driver currently supports the chips with the Loongson GMAC network
> > device. As a preparation before adding the Loongson GNET support
> > detach the Loongson GMAC-specific platform data initializations to the
> > loongson_gmac_data() method and preserve the common settings in the
> > loongson_default_data().
> > 
> > While at it drop the return value statement from the
> > loongson_default_data() method as redundant."
> OK, Thanks!
> > 
> > > Signed-off-by: Feiyang Chen <chenfeiyang@...ngson.cn>
> > > Signed-off-by: Yinggang Gu <guyinggang@...ngson.cn>
> > > Signed-off-by: Yanteng Si <siyanteng@...ngson.cn>
> > > ---
> > >   .../ethernet/stmicro/stmmac/dwmac-loongson.c  | 20 ++++++++++++-------
> > >   1 file changed, 13 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
> > > index 4e0838db4259..904e288d0be0 100644
> > > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
> > > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
> > > @@ -11,22 +11,20 @@
> > >   #define PCI_DEVICE_ID_LOONGSON_GMAC	0x7a03
> > > -static int loongson_default_data(struct plat_stmmacenet_data *plat)
> > > +static void loongson_default_data(struct plat_stmmacenet_data *plat)
> > >   {
> > >   	plat->clk_csr = 2;	/* clk_csr_i = 20-35MHz & MDC = clk_csr_i/16 */
> > >   	plat->has_gmac = 1;
> > >   	plat->force_sf_dma_mode = 1;
> > > +	plat->mac_interface = PHY_INTERFACE_MODE_GMII;
> > > +
> > I double-checked this part in my HW and in the databooks. DW GMAC with
> > _RGMII_ PHY-interfaces can't be equipped with a PCS (STMMAC driver is
> > wrong in considering otherwise at least in the Auto-negotiation part).
> > PCS is only available for the RTI, RTBI and SGMII interfaces.
> > 
> > You can double-check that by checking out the DMA_HW_FEATURE.PCSSEL
> > flag state. I'll be surprised if it's set in your case. If it isn't
> > then either drop the plat_stmmacenet_data::mac_interface
> > initialization or (as Russell suggested) initialize it with
> > PHY_INTERFACE_MODE_NA. But do that in a separate pre-requisite patch!
> OK.
> > 
> > >   	/* Set default value for unicast filter entries */
> > >   	plat->unicast_filter_entries = 1;
> > >   	/* Set the maxmtu to a default of JUMBO_LEN */
> > >   	plat->maxmtu = JUMBO_LEN;
> > > -	/* Set default number of RX and TX queues to use */
> > > -	plat->tx_queues_to_use = 1;
> > > -	plat->rx_queues_to_use = 1;
> > > -
> > >   	/* Disable Priority config by default */
> > >   	plat->tx_queues_cfg[0].use_prio = false;
> > >   	plat->rx_queues_cfg[0].use_prio = false;
> > > @@ -41,6 +39,12 @@ static int loongson_default_data(struct plat_stmmacenet_data *plat)
> > >   	plat->dma_cfg->pblx8 = true;
> > >   	plat->multicast_filter_bins = 256;
> > > +}
> > > +
> > > +static int loongson_gmac_data(struct plat_stmmacenet_data *plat)
> > > +{
> > > +	loongson_default_data(plat);
> > > +
> > >   	return 0;
> > >   }
> > > @@ -109,11 +113,10 @@ static int loongson_dwmac_probe(struct pci_dev *pdev, const struct pci_device_id
> > >   	}
> > >   	plat->phy_interface = phy_mode;
> > > -	plat->mac_interface = PHY_INTERFACE_MODE_GMII;
> > >   	pci_set_master(pdev);
> > > -	loongson_default_data(plat);
> > > +	loongson_gmac_data(plat);
> > >   	pci_enable_msi(pdev);
> > >   	memset(&res, 0, sizeof(res));
> > >   	res.addr = pcim_iomap_table(pdev)[0];
> > > @@ -138,6 +141,9 @@ static int loongson_dwmac_probe(struct pci_dev *pdev, const struct pci_device_id
> > >   		goto err_disable_msi;
> > >   	}
> > > +	plat->tx_queues_to_use = 1;
> > > +	plat->rx_queues_to_use = 1;
> > > +
> > You can freely move this to loongson_gmac_data() method. And then, in
> > the patch adding the GNET-support, you'll be able to provide these fields
> > initialization in the loongson_gnet_data() method together with the
> > plat->tx_queues_cfg[*].coe_unsupported flag init. Thus the probe()
> > method will get to be smaller and easier to read, and the
> > loongson_*_data() method will be more coherent.
> 
> As you said, at first glance, putting them in loongson_gnet_data() method is
> fine,
> 
> but in LS2K2000:
> 
>         plat->rx_queues_to_use = CHANNEL_NUM;    // CHANNEL_NUM = 8;
>         plat->tx_queues_to_use = CHANNEL_NUM;
> 
> So we need to distinguish between them. At the same time, we have to
> distinguish
> 
> between LS2K2000 in probe() method. Why not put them inside probe, which
> will
> 
> save a lot of duplicate code, like this:
> 
>     struct stmmac_resources res;
>     struct loongson_data *ld;
> 
> ...
> 
>     memset(&res, 0, sizeof(res));
>     res.addr = pcim_iomap_table(pdev)[0];
>     ld->gmac_verion = readl(res.addr + GMAC_VERSION) & 0xff;
> 
>     switch (ld->gmac_verion) {
>     case LOONGSON_DWMAC_CORE_1_00:
>         plat->rx_queues_to_use = CHANNEL_NUM;
>         plat->tx_queues_to_use = CHANNEL_NUM;
> 
>         /* Only channel 0 supports checksum,
>          * so turn off checksum to enable multiple channels.
>          */
>         for (i = 1; i < CHANNEL_NUM; i++)
>             plat->tx_queues_cfg[i].coe_unsupported = 1;
> 
>         ret = loongson_dwmac_config_msi(pdev, plat, &res, np);
>         break;
>     default:    /* 0x35 device and 0x37 device. */
>         plat->tx_queues_to_use = 1;
>         plat->rx_queues_to_use = 1;
> 
>         ret = loongson_dwmac_config_legacy(pdev, plat, &res, np);
>         break;
>     }
>     if (ret)
>         goto err_disable_device;
> 
> 
> What do you think?
> 
> 
> Of course, if you insist, I'm willing to repeat this in the
> 
> loongson_gnet_data() method.

Not necessarily. As Huacai earlier suggested you can keep the Loongson
ID in the platform private data and have it utilized in the local
sub-functions/routines. Like this:

struct loongson_data {
	u32 loongson_id;
};

static int loongson_gmac_data(struct pci_dev *pdev,
			      struct plat_stmmacenet_data *plat)
{
	struct loongson_data *ld = plat->bsp_priv;

	...

	plat->rx_queues_to_use = 1;
	plat->tx_queues_to_use = 1;

	return 0;
}

static int loongson_gnet_data(struct pci_dev *pdev,
			      struct plat_stmmacenet_data *plat)
{
	struct loongson_data *ld = plat->bsp_priv;

	...

	if (ld->loongson_id == DWMAC_CORE_LS2K2000) {
		plat->rx_queues_to_use = 8;
		plat->tx_queues_to_use = 8;

		/* Tx COE is supported by the channel 0 only */
		for (i = 1; i < 8; i++)
			plat->tx_queues_cfg[i].coe_unsupported = 1;
	} else {
		plat->rx_queues_to_use = 1;
		plat->tx_queues_to_use = 1;
	}

	return 0;
}

static int loongson_dwmac_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
	struct loongson_data *ld;
	...

	ld = devm_kzalloc(&pdev->dev, sizeof(*ld), GFP_KERNEL);
	if (!ld)
		return -ENOMEM;
	...
	ld->loongson_id = readl(res.addr + GMAC_VERSION) & 0xff;
	plat->bsp_priv = ld;
	...
	if (ld->loongson_id == DWMAC_CORE_LS2K2000)
		ret = loongson_dwmac_config_msi(pdev, plat, &res);
	else
		ret = loongson_dwmac_config_plat(pdev, plat, &res);

	if (ret)
		return ret;
	...
}

It's not "a lot" duplication code. Just two if-else statements, which
is fine. But the data-init methods will get to be fully coherent. It's
much more important.

* Note switch-case is redundant since you have a single case in there,
so if-else would be more than enough.

-Serge(y)

> 
> 
> 
> Thanks,
> 
> Yanteng
> 

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