Re: [PATCH v2 05/11] net: stmmac: dwmac-stm32: update config management for phy wo cristal

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On 4/26/24 2:57 PM, Christophe Roullier wrote:
Some cleaning because some Ethernet PHY configs do not need to add
st,ext-phyclk property.
Change print info message "No phy clock provided" only when debug.

Signed-off-by: Christophe Roullier <christophe.roullier@xxxxxxxxxxx>
---
  .../net/ethernet/stmicro/stmmac/dwmac-stm32.c | 27 ++++++++++---------
  1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
index 7529a8d15492..e648c4e790a7 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-stm32.c
@@ -55,17 +55,17 @@
   *|         |        |      25MHz    |        50MHz       |                  |
   * ---------------------------------------------------------------------------
   *|  MII    |	 -   |     eth-ck    |	      n/a	  |	  n/a        |
- *|         |        | st,ext-phyclk |                    |		     |
+ *|         |        |	             |                    |		     |
   * ---------------------------------------------------------------------------
   *|  GMII   |	 -   |     eth-ck    |	      n/a	  |	  n/a        |
- *|         |        | st,ext-phyclk |                    |		     |
+ *|         |        |               |                    |		     |
   * ---------------------------------------------------------------------------
   *| RGMII   |	 -   |     eth-ck    |	      n/a	  |      eth-ck      |
- *|         |        | st,ext-phyclk |                    | st,eth-clk-sel or|
+ *|         |        |               |                    | st,eth-clk-sel or|
   *|         |        |               |                    | st,ext-phyclk    |
   * ---------------------------------------------------------------------------
   *| RMII    |	 -   |     eth-ck    |	    eth-ck        |	  n/a        |
- *|         |        | st,ext-phyclk | st,eth-ref-clk-sel |		     |
+ *|         |        |               | st,eth-ref-clk-sel |		     |
   *|         |        |               | or st,ext-phyclk   |		     |
   * ---------------------------------------------------------------------------
   *
@@ -174,23 +174,22 @@ static int stm32mp1_set_mode(struct plat_stmmacenet_data *plat_dat)
  	dwmac->enable_eth_ck = false;
  	switch (plat_dat->mac_interface) {
  	case PHY_INTERFACE_MODE_MII:
-		if (clk_rate == ETH_CK_F_25M && dwmac->ext_phyclk)
+		if (clk_rate == ETH_CK_F_25M)

I see two problems here.

First, according to the table above, in MII mode, clk_rate cannot be anything else but 25 MHz, so the (clk_rate == ETH_CK_F_25M) condition is always true. Why not drop that condition ?

The "dwmac->ext_phyclk" means "Ethernet PHY have no crystal", which means the clock are provided by the STM32 RCC clock IP instead, which means if the dwmac->ext_phyclk is true, dwmac->enable_eth_ck should be set to true, because dwmac->enable_eth_ck controls the enablement of these STM32 clock IP generated clock.

Second, as far as I understand it, there is no way to operate this IP with external clock in MII mode, so this section should always be only:

dwmac->enable_eth_ck = true;

  			dwmac->enable_eth_ck = true;
  		val = dwmac->ops->pmcsetr.eth1_selmii;
  		pr_debug("SYSCFG init : PHY_INTERFACE_MODE_MII\n");
  		break;
  	case PHY_INTERFACE_MODE_GMII:
  		val = SYSCFG_PMCR_ETH_SEL_GMII;
-		if (clk_rate == ETH_CK_F_25M &&
-		    (dwmac->eth_clk_sel_reg || dwmac->ext_phyclk)) {
+		if (clk_rate == ETH_CK_F_25M)
  			dwmac->enable_eth_ck = true;
-			val |= dwmac->ops->pmcsetr.eth1_clk_sel;
-		}
  		pr_debug("SYSCFG init : PHY_INTERFACE_MODE_GMII\n");
  		break;
  	case PHY_INTERFACE_MODE_RMII:
  		val = dwmac->ops->pmcsetr.eth1_sel_rmii | dwmac->ops->pmcsetr.eth2_sel_rmii;
-		if ((clk_rate == ETH_CK_F_25M || clk_rate == ETH_CK_F_50M) &&
+		if (clk_rate == ETH_CK_F_25M)
+			dwmac->enable_eth_ck = true;
+		if (clk_rate == ETH_CK_F_50M &&
  		    (dwmac->eth_ref_clk_sel_reg || dwmac->ext_phyclk)) {

This doesn't seem to be equivalent change to the previous code . Here, if the clock frequency is 25 MHz, the clock are unconditionally enabled. Before, the code enabled the clock only if clock frequency was 25 MHz AND one of the "dwmac->eth_ref_clk_sel_reg" or "dwmac->ext_phyclk" was set (i.e. clock provided by SoC RCC clock IP).

I think it might make this code easier if you drop all of the frequency test conditionals, which aren't really all that useful, and only enable the clock if either dwmac->ext_phyclk / dwmac->eth_clk_sel_reg / dwmac->eth_ref_clk_sel_reg is set , because effectively what this entire convoluted code is implementing is "if (clock supplied by clock IP i.e. RCC) enable the clock()" *, right ?

* And it is also toggling the right clock mux bit in PMCSETR.

So, for MII this would be plain:
dwmac->enable_eth_ck = true;

For GMII/RGMII this would be:
if (dwmac->ext_phyclk || dwmac->eth_clk_sel_reg)
  dwmac->enable_eth_ck = true;

For RMII this would be:
if (dwmac->ext_phyclk || dwmac->eth_ref_clk_sel_reg)
  dwmac->enable_eth_ck = true;

Maybe the clock frequency validation can be retained, but done separately?

  			dwmac->enable_eth_ck = true;
  			val |= dwmac->ops->pmcsetr.eth1_ref_clk_sel;
@@ -203,7 +202,9 @@ static int stm32mp1_set_mode(struct plat_stmmacenet_data *plat_dat)
  	case PHY_INTERFACE_MODE_RGMII_RXID:
  	case PHY_INTERFACE_MODE_RGMII_TXID:
  		val = dwmac->ops->pmcsetr.eth1_sel_rgmii | dwmac->ops->pmcsetr.eth2_sel_rgmii;
-		if ((clk_rate == ETH_CK_F_25M || clk_rate == ETH_CK_F_125M) &&
+		if (clk_rate == ETH_CK_F_25M)
+			dwmac->enable_eth_ck = true;
+		if (clk_rate == ETH_CK_F_125M &&
  		    (dwmac->eth_clk_sel_reg || dwmac->ext_phyclk)) {
  			dwmac->enable_eth_ck = true;
  			val |= dwmac->ops->pmcsetr.eth1_clk_sel;
@@ -219,7 +220,7 @@ static int stm32mp1_set_mode(struct plat_stmmacenet_data *plat_dat)
  	}
/* Need to update PMCCLRR (clear register) */
-	regmap_write(dwmac->regmap, reg + dwmac->ops->syscfg_clr_off,
+	regmap_write(dwmac->regmap, dwmac->ops->syscfg_clr_off,
  		     dwmac->mode_mask);
/* Update PMCSETR (set register) */
@@ -328,7 +329,7 @@ static int stm32mp1_parse_data(struct stm32_dwmac *dwmac,
  	/*  Get ETH_CLK clocks */
  	dwmac->clk_eth_ck = devm_clk_get(dev, "eth-ck");
  	if (IS_ERR(dwmac->clk_eth_ck)) {
-		dev_info(dev, "No phy clock provided...\n");
+		dev_dbg(dev, "No phy clock provided...\n");
  		dwmac->clk_eth_ck = NULL;
  	}




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