2023-07-11 21:12:09

by Andrew Halaney

Subject: [PATCH RFC/RFT net-next 2/3] net: stmmac: dwmac-qcom-ethqos: Use max frequency for clk_ptp_ref

Qualcomm clocks can set their frequency to a variety of levels
generally. Let's use the max for clk_ptp_ref to ensure the best
timestamping resolution possible.

Without this, the default value of the clock is used. For sa8775p-ride
this is 19.2 MHz, far less than the 230.4 MHz possible.

Signed-off-by: Andrew Halaney <[email protected]>
---
.../stmicro/stmmac/dwmac-qcom-ethqos.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
index 757504ebb676..f9e7440520fa 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
@@ -694,6 +694,23 @@ static void ethqos_clks_disable(void *data)
ethqos_clks_config(data, false);
}

+static void ethqos_ptp_clk_freq_config(struct stmmac_priv *priv)
+{
+ struct plat_stmmacenet_data *plat_dat = priv->plat;
+ int err;
+
+ if (!plat_dat->clk_ptp_ref)
+ return;
+
+ /* Max the PTP ref clock out to get the best resolution possible */
+ err = clk_set_rate(plat_dat->clk_ptp_ref, ULONG_MAX);
+ if (err)
+ netdev_err(priv->dev, "Failed to max out clk_ptp_ref: %d\n", err);
+ plat_dat->clk_ptp_rate = clk_get_rate(plat_dat->clk_ptp_ref);
+
+ netdev_dbg(priv->dev, "PTP rate %d\n", plat_dat->clk_ptp_rate);
+}
+
static int qcom_ethqos_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
@@ -779,6 +796,7 @@ static int qcom_ethqos_probe(struct platform_device *pdev)
plat_dat->bsp_priv = ethqos;
plat_dat->fix_mac_speed = ethqos_fix_mac_speed;
plat_dat->dump_debug_regs = rgmii_dump;
+ plat_dat->ptp_clk_freq_config = ethqos_ptp_clk_freq_config;
plat_dat->has_gmac4 = 1;
if (ethqos->has_emac_ge_3)
plat_dat->dwmac4_addrs = &data->dwmac4_addrs;
--
2.41.0

2023-07-13 10:06:36

by Simon Horman

Subject: Re: [PATCH RFC/RFT net-next 2/3] net: stmmac: dwmac-qcom-ethqos: Use max frequency for clk_ptp_ref

On Tue, Jul 11, 2023 at 03:35:31PM -0500, Andrew Halaney wrote:
> Qualcomm clocks can set their frequency to a variety of levels
> generally. Let's use the max for clk_ptp_ref to ensure the best
> timestamping resolution possible.
>
> Without this, the default value of the clock is used. For sa8775p-ride
> this is 19.2 MHz, far less than the 230.4 MHz possible.
>
> Signed-off-by: Andrew Halaney <[email protected]>

Reviewed-by: Simon Horman <[email protected]>