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Message-ID: <vxcfrxtbfu4pya56m22icnizsyjzqqha5blzb7zpexqcur56uh@uv6vsjf77npa>
Date: Thu, 21 Dec 2023 01:36:20 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: Yanteng Si <siyanteng@...ngson.cn>
Cc: andrew@...n.ch, hkallweit1@...il.com, peppe.cavallaro@...com, 
	alexandre.torgue@...s.st.com, joabreu@...opsys.com, Jose.Abreu@...opsys.com, 
	chenhuacai@...ngson.cn, linux@...linux.org.uk, guyinggang@...ngson.cn, 
	netdev@...r.kernel.org, chris.chenfeiyang@...il.com
Subject: Re: [PATCH net-next v7 4/9] net: stmmac: Add multi-channel supports

On Tue, Dec 19, 2023 at 10:17:07PM +0800, Yanteng Si wrote:
> Loongson platforms use a DWGMAC which supports multi-channel.
> 
> Added dwmac1000_dma_init_channel() and init_chan(), factor out
> all the channel-specific setups from dwmac1000_dma_init() to the
> new function dma_config(), then distinguish dma initialization
> and multi-channel initialization through different parameters.
> 
> Signed-off-by: Yanteng Si <siyanteng@...ngson.cn>
> Signed-off-by: Feiyang Chen <chenfeiyang@...ngson.cn>
> Signed-off-by: Yinggang Gu <guyinggang@...ngson.cn>
> ---
>  .../ethernet/stmicro/stmmac/dwmac1000_dma.c   | 55 ++++++++++++++-----
>  .../net/ethernet/stmicro/stmmac/dwmac_dma.h   | 17 ++++++
>  .../net/ethernet/stmicro/stmmac/dwmac_lib.c   | 30 +++++-----
>  3 files changed, 74 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
> index 5e80d3eec9db..0fb48e683970 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_dma.c
> @@ -12,7 +12,8 @@
>    Author: Giuseppe Cavallaro <peppe.cavallaro@...com>
>  *******************************************************************************/
>  
> -#include <asm/io.h>
> +#include <linux/io.h>
> +#include "stmmac.h"
>  #include "dwmac1000.h"
>  #include "dwmac_dma.h"
>  
> @@ -70,13 +71,16 @@ static void dwmac1000_dma_axi(void __iomem *ioaddr, struct stmmac_axi *axi)
>  	writel(value, ioaddr + DMA_AXI_BUS_MODE);
>  }
>  
> -static void dwmac1000_dma_init(struct stmmac_priv *priv, void __iomem *ioaddr,
> -			       struct stmmac_dma_cfg *dma_cfg, int atds)

> +static void dma_config(void __iomem *modeaddr, void __iomem *enaddr,
> +					   struct stmmac_dma_cfg *dma_cfg, u32 dma_intr_mask,
> +					   int atds)

Please make sure the arguments are aligned with the function open
parenthesis taking into account that tabs are of _8_ chars:
Documentation/process/coding-style.rst.

>  {
> -	u32 value = readl(ioaddr + DMA_BUS_MODE);
> +	u32 value;
>  	int txpbl = dma_cfg->txpbl ?: dma_cfg->pbl;
>  	int rxpbl = dma_cfg->rxpbl ?: dma_cfg->pbl;
>  
> +	value = readl(modeaddr);
> +
>  	/*
>  	 * Set the DMA PBL (Programmable Burst Length) mode.
>  	 *
> @@ -104,10 +108,34 @@ static void dwmac1000_dma_init(struct stmmac_priv *priv, void __iomem *ioaddr,
>  	if (dma_cfg->aal)
>  		value |= DMA_BUS_MODE_AAL;
>  
> -	writel(value, ioaddr + DMA_BUS_MODE);
> +	writel(value, modeaddr);
> +	writel(dma_intr_mask, enaddr);
> +}
> +

> +static void dwmac1000_dma_init(struct stmmac_priv *priv, void __iomem *ioaddr,
> +							   struct stmmac_dma_cfg *dma_cfg, int atds)
> +{
> +	u32 dma_intr_mask;
>  
>  	/* Mask interrupts by writing to CSR7 */
> -	writel(DMA_INTR_DEFAULT_MASK, ioaddr + DMA_INTR_ENA);
> +	dma_intr_mask = DMA_INTR_DEFAULT_MASK;
> +
> +	dma_config(ioaddr + DMA_BUS_MODE, ioaddr + DMA_INTR_ENA,
> +			  dma_cfg, dma_intr_mask, atds);
> +}
> +
> +static void dwmac1000_dma_init_channel(struct stmmac_priv *priv, void __iomem *ioaddr,
> +									   struct stmmac_dma_cfg *dma_cfg, u32 chan)
> +{
> +	u32 dma_intr_mask;
> +
> +	/* Mask interrupts by writing to CSR7 */
> +	dma_intr_mask = DMA_INTR_DEFAULT_MASK;
> +
> +	if (dma_cfg->multi_msi_en)
> +		dma_config(ioaddr + DMA_CHAN_BUS_MODE(chan),
> +					ioaddr + DMA_CHAN_INTR_ENA(chan), dma_cfg,

Why so complicated? stmmac_init_chan() is always supposed to be called
in the same context as stmmac_dma_init() (stmmac_xdp_open() is wrong
in not doing that). Seeing DW GMAC v3.x multi-channels feature is
implemented as multiple sets of the same CSRs (except AV traffic
control CSRs specific to channels 1 and higher which are left unused
here anyway) you can just drop the stmmac_dma_ops.init() callback and
convert dwmac1000_dma_init() to being dwmac1000_dma_init_channel()
with no significant modifications:

< you wouldn't need to have a separate dma_config() method.
< you wouldn't need to check for the dma_cfg->multi_msi_en flag state
since the stmmac_init_chan() method is called for as many times as
there are channels available (at least 1 channel always exists).
< just add atds argument.
< just convert the method to using the chan-dependent CSR macros.

> +					dma_intr_mask, dma_cfg->multi_msi_en);
                                                                ^
              +-------------------------------------------------+
This is wrong + ATDS flag means Alternative Descriptor Size. This flag
enables the 8 dword DMA-descriptors size with some DMA-desc fields
semantics changed (see enh_desc.c and norm_desc.c). It's useful for
PTP Timestamping, VLANs, AV feature, L3/L4 filtering, CSum offload
Type 2 (if any of that available). It has nothing to do with the
separate DMA IRQs. Just convert the stmmac_dma_ops.dma_init() callback
to accepting the atds flag as an additional argument, use it here to
activate the extended descriptor size and make sure the atds flag is
passed to the stmmac_init_chan() method in the respective source code.

>  }
>  
>  static void dwmac1000_dma_init_rx(struct stmmac_priv *priv,
> @@ -116,7 +144,7 @@ static void dwmac1000_dma_init_rx(struct stmmac_priv *priv,
>  				  dma_addr_t dma_rx_phy, u32 chan)
>  {
>  	/* RX descriptor base address list must be written into DMA CSR3 */
> -	writel(lower_32_bits(dma_rx_phy), ioaddr + DMA_RCV_BASE_ADDR);
> +	writel(lower_32_bits(dma_rx_phy), ioaddr + DMA_CHAN_RCV_BASE_ADDR(chan));
>  }
>  
>  static void dwmac1000_dma_init_tx(struct stmmac_priv *priv,
> @@ -125,7 +153,7 @@ static void dwmac1000_dma_init_tx(struct stmmac_priv *priv,
>  				  dma_addr_t dma_tx_phy, u32 chan)
>  {
>  	/* TX descriptor base address list must be written into DMA CSR4 */
> -	writel(lower_32_bits(dma_tx_phy), ioaddr + DMA_TX_BASE_ADDR);
> +	writel(lower_32_bits(dma_tx_phy), ioaddr + DMA_CHAN_TX_BASE_ADDR(chan));
>  }
>  
>  static u32 dwmac1000_configure_fc(u32 csr6, int rxfifosz)
> @@ -153,7 +181,7 @@ static void dwmac1000_dma_operation_mode_rx(struct stmmac_priv *priv,
>  					    void __iomem *ioaddr, int mode,
>  					    u32 channel, int fifosz, u8 qmode)
>  {
> -	u32 csr6 = readl(ioaddr + DMA_CONTROL);
> +	u32 csr6 = readl(ioaddr + DMA_CHAN_CONTROL(channel));
>  
>  	if (mode == SF_DMA_MODE) {
>  		pr_debug("GMAC: enable RX store and forward mode\n");
> @@ -175,14 +203,14 @@ static void dwmac1000_dma_operation_mode_rx(struct stmmac_priv *priv,
>  	/* Configure flow control based on rx fifo size */
>  	csr6 = dwmac1000_configure_fc(csr6, fifosz);
>  
> -	writel(csr6, ioaddr + DMA_CONTROL);
> +	writel(csr6, ioaddr + DMA_CHAN_CONTROL(channel));
>  }
>  
>  static void dwmac1000_dma_operation_mode_tx(struct stmmac_priv *priv,
>  					    void __iomem *ioaddr, int mode,
>  					    u32 channel, int fifosz, u8 qmode)
>  {
> -	u32 csr6 = readl(ioaddr + DMA_CONTROL);
> +	u32 csr6 = readl(ioaddr + DMA_CHAN_CONTROL(channel));
>  
>  	if (mode == SF_DMA_MODE) {
>  		pr_debug("GMAC: enable TX store and forward mode\n");
> @@ -209,7 +237,7 @@ static void dwmac1000_dma_operation_mode_tx(struct stmmac_priv *priv,
>  			csr6 |= DMA_CONTROL_TTC_256;
>  	}
>  
> -	writel(csr6, ioaddr + DMA_CONTROL);
> +	writel(csr6, ioaddr + DMA_CHAN_CONTROL(channel));
>  }
>  
>  static void dwmac1000_dump_dma_regs(struct stmmac_priv *priv,
> @@ -271,12 +299,13 @@ static int dwmac1000_get_hw_feature(void __iomem *ioaddr,
>  static void dwmac1000_rx_watchdog(struct stmmac_priv *priv,
>  				  void __iomem *ioaddr, u32 riwt, u32 queue)
>  {
> -	writel(riwt, ioaddr + DMA_RX_WATCHDOG);
> +	writel(riwt, ioaddr + DMA_CHAN_RX_WATCHDOG(queue));
>  }
>  
>  const struct stmmac_dma_ops dwmac1000_dma_ops = {
>  	.reset = dwmac_dma_reset,

>  	.init = dwmac1000_dma_init,

This could be dropped. See my comment above.

> +	.init_chan = dwmac1000_dma_init_channel,
>  	.init_rx_chan = dwmac1000_dma_init_rx,
>  	.init_tx_chan = dwmac1000_dma_init_tx,
>  	.axi = dwmac1000_dma_axi,
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac_dma.h b/drivers/net/ethernet/stmicro/stmmac/dwmac_dma.h
> index e7aef136824b..395d5e4c3922 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac_dma.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac_dma.h
> @@ -148,6 +148,9 @@
>  					 DMA_STATUS_TI | \
>  					 DMA_STATUS_MSK_COMMON)
>  

> +/* Following DMA defines are chanels oriented */

s/chanels/channels

> +#define DMA_CHAN_OFFSET			0x100

DMA_CHAN_BASE_OFFSET? to be looking the same as in DW QoS Eth GMAC
v4.x/v5.x (dwmac4_dma.h).

> +
>  #define NUM_DWMAC100_DMA_REGS	9
>  #define NUM_DWMAC1000_DMA_REGS	23
>  #define NUM_DWMAC4_DMA_REGS	27
> @@ -170,4 +173,18 @@ int dwmac_dma_interrupt(struct stmmac_priv *priv, void __iomem *ioaddr,
>  			struct stmmac_extra_stats *x, u32 chan, u32 dir);
>  int dwmac_dma_reset(void __iomem *ioaddr);
>  
> +static inline u32 dma_chan_base_addr(u32 base, u32 chan)
> +{
> +	return base + chan * DMA_CHAN_OFFSET;
> +}
> +
> +#define DMA_CHAN_XMT_POLL_DEMAND(chan)	dma_chan_base_addr(DMA_XMT_POLL_DEMAND, chan)
> +#define DMA_CHAN_INTR_ENA(chan)		dma_chan_base_addr(DMA_INTR_ENA, chan)
> +#define DMA_CHAN_CONTROL(chan)		dma_chan_base_addr(DMA_CONTROL, chan)
> +#define DMA_CHAN_STATUS(chan)		dma_chan_base_addr(DMA_STATUS, chan)
> +#define DMA_CHAN_BUS_MODE(chan)		dma_chan_base_addr(DMA_BUS_MODE, chan)
> +#define DMA_CHAN_RCV_BASE_ADDR(chan)	dma_chan_base_addr(DMA_RCV_BASE_ADDR, chan)
> +#define DMA_CHAN_TX_BASE_ADDR(chan)	dma_chan_base_addr(DMA_TX_BASE_ADDR, chan)
> +#define DMA_CHAN_RX_WATCHDOG(chan)	dma_chan_base_addr(DMA_RX_WATCHDOG, chan)
> +
>  #endif /* __DWMAC_DMA_H__ */
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c
> index 2f0df16fb7e4..968801c694e9 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac_lib.c
> @@ -31,63 +31,63 @@ int dwmac_dma_reset(void __iomem *ioaddr)
>  void dwmac_enable_dma_transmission(struct stmmac_priv *priv,
>  				   void __iomem *ioaddr, u32 chan)
>  {
> -	writel(1, ioaddr + DMA_XMT_POLL_DEMAND);
> +	writel(1, ioaddr + DMA_CHAN_XMT_POLL_DEMAND(chan));
>  }
>  
>  void dwmac_enable_dma_irq(struct stmmac_priv *priv, void __iomem *ioaddr,
>  			  u32 chan, bool rx, bool tx)
>  {
> -	u32 value = readl(ioaddr + DMA_INTR_ENA);
> +	u32 value = readl(ioaddr + DMA_CHAN_INTR_ENA(chan));
>  
>  	if (rx)
>  		value |= DMA_INTR_DEFAULT_RX;
>  	if (tx)
>  		value |= DMA_INTR_DEFAULT_TX;
>  
> -	writel(value, ioaddr + DMA_INTR_ENA);
> +	writel(value, ioaddr + DMA_CHAN_INTR_ENA(chan));
>  }
>  
>  void dwmac_disable_dma_irq(struct stmmac_priv *priv, void __iomem *ioaddr,
>  			   u32 chan, bool rx, bool tx)
>  {
> -	u32 value = readl(ioaddr + DMA_INTR_ENA);
> +	u32 value = readl(ioaddr + DMA_CHAN_INTR_ENA(chan));
>  
>  	if (rx)
>  		value &= ~DMA_INTR_DEFAULT_RX;
>  	if (tx)
>  		value &= ~DMA_INTR_DEFAULT_TX;
>  
> -	writel(value, ioaddr + DMA_INTR_ENA);
> +	writel(value, ioaddr + DMA_CHAN_INTR_ENA(chan));
>  }
>  
>  void dwmac_dma_start_tx(struct stmmac_priv *priv, void __iomem *ioaddr,
>  			u32 chan)
>  {
> -	u32 value = readl(ioaddr + DMA_CONTROL);
> +	u32 value = readl(ioaddr + DMA_CHAN_CONTROL(chan));
>  	value |= DMA_CONTROL_ST;
> -	writel(value, ioaddr + DMA_CONTROL);
> +	writel(value, ioaddr + DMA_CHAN_CONTROL(chan));
>  }
>  
>  void dwmac_dma_stop_tx(struct stmmac_priv *priv, void __iomem *ioaddr, u32 chan)
>  {
> -	u32 value = readl(ioaddr + DMA_CONTROL);
> +	u32 value = readl(ioaddr + DMA_CHAN_CONTROL(chan));
>  	value &= ~DMA_CONTROL_ST;
> -	writel(value, ioaddr + DMA_CONTROL);
> +	writel(value, ioaddr + DMA_CHAN_CONTROL(chan));
>  }
>  
>  void dwmac_dma_start_rx(struct stmmac_priv *priv, void __iomem *ioaddr,
>  			u32 chan)
>  {
> -	u32 value = readl(ioaddr + DMA_CONTROL);
> +	u32 value = readl(ioaddr + DMA_CHAN_CONTROL(chan));
>  	value |= DMA_CONTROL_SR;
> -	writel(value, ioaddr + DMA_CONTROL);
> +	writel(value, ioaddr + DMA_CHAN_CONTROL(chan));
>  }
>  
>  void dwmac_dma_stop_rx(struct stmmac_priv *priv, void __iomem *ioaddr, u32 chan)
>  {
> -	u32 value = readl(ioaddr + DMA_CONTROL);
> +	u32 value = readl(ioaddr + DMA_CHAN_CONTROL(chan));
>  	value &= ~DMA_CONTROL_SR;
> -	writel(value, ioaddr + DMA_CONTROL);
> +	writel(value, ioaddr + DMA_CHAN_CONTROL(chan));
>  }
>  
>  #ifdef DWMAC_DMA_DEBUG
> @@ -167,7 +167,7 @@ int dwmac_dma_interrupt(struct stmmac_priv *priv, void __iomem *ioaddr,
>  	struct stmmac_txq_stats *txq_stats = &priv->xstats.txq_stats[chan];
>  	int ret = 0;
>  	/* read the status register (CSR5) */
> -	u32 intr_status = readl(ioaddr + DMA_STATUS);
> +	u32 intr_status = readl(ioaddr + DMA_CHAN_STATUS(chan));
>  
>  #ifdef DWMAC_DMA_DEBUG
>  	/* Enable it to monitor DMA rx/tx status in case of critical problems */
> @@ -237,7 +237,7 @@ int dwmac_dma_interrupt(struct stmmac_priv *priv, void __iomem *ioaddr,
>  		pr_warn("%s: unexpected status %08x\n", __func__, intr_status);
>  
>  	/* Clear the interrupt by writing a logic 1 to the CSR5[15-0] */

> -	writel((intr_status & 0x1ffff), ioaddr + DMA_STATUS);
> +	writel((intr_status & 0x7ffff), ioaddr + DMA_CHAN_STATUS(chan));

Em, please explain the mask change. Bits CSR5[17:28] are defined as RO
on a normal DW GMAC. Anyway it seems like the mask changes belongs to
the patch 5/9.


Except the last comment, AFAICS this patch provides a generic DW GMAC
v3.x multi-channel support. Despite of several issues noted above the
change in general looks very good.

-Serge(y)

>  
>  	return ret;
>  }
> -- 
> 2.31.4
> 

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