Re: [PATCH v10 3/5] drm/msm/dp: add support for DP PLL driver

From: Dmitry Baryshkov
Date: Sat Aug 15 2020 - 17:51:46 EST

On 15/08/2020 02:22, Tanmay Shah wrote:
On 2020-08-14 10:05, Dmitry Baryshkov wrote:
On 12/08/2020 07:42, Tanmay Shah wrote:
From: Chandan Uddaraju <chandanu@xxxxxxxxxxxxxx>

Add the needed DP PLL specific files to support
display port interface on msm targets.

[skipped]

diff --git a/drivers/gpu/drm/msm/dp/dp_pll_private.h b/drivers/gpu/drm/msm/dp/dp_pll_private.h
new file mode 100644
index 000000000000..475ba6ed59ab
--- /dev/null
+++ b/drivers/gpu/drm/msm/dp/dp_pll_private.h
@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2016-2020, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef __DP_PLL_10NM_H
+#define __DP_PLL_10NM_H
+
+#include "dp_pll.h"
+#include "dp_reg.h"
+
+#define DP_VCO_HSCLK_RATE_1620MHZDIV1000    1620000UL
+#define DP_VCO_HSCLK_RATE_2700MHZDIV1000    2700000UL
+#define DP_VCO_HSCLK_RATE_5400MHZDIV1000    5400000UL
+#define DP_VCO_HSCLK_RATE_8100MHZDIV1000    8100000UL
+
+#define NUM_DP_CLOCKS_MAX            6
+
+#define DP_PHY_PLL_POLL_SLEEP_US        500
+#define DP_PHY_PLL_POLL_TIMEOUT_US        10000
+
+#define DP_VCO_RATE_8100MHZDIV1000        8100000UL
+#define DP_VCO_RATE_9720MHZDIV1000        9720000UL
+#define DP_VCO_RATE_10800MHZDIV1000        10800000UL
+
+struct dp_pll_vco_clk {
+    struct clk_hw hw;
+    unsigned long    rate;        /* current vco rate */
+    u64        min_rate;    /* min vco rate */
+    u64        max_rate;    /* max vco rate */
+    void        *priv;
+};
+
+struct dp_pll_db {

This struct should probably go into dp_pll_10nm.c. dp_pll_7nm.c, for
example, will use slightly different structure.


Sure, it sounds good. I will give it try. Thanks!

+    struct msm_dp_pll *base;
+
+    int id;
+    struct platform_device *pdev;
+
+    /* private clocks: */
+    bool fixed_factor_clk[NUM_DP_CLOCKS_MAX];
+    struct clk_hw *hws[NUM_DP_CLOCKS_MAX];

Then these two fields can use exact number of clocks rather than
NUM_DP_CLOCKS_MAX.


I didn't get this. I think NUM_DP_CLOCKS_MAX is doing same?

Not exactly. We'd need fixed_factor_clk[4] for 10nm rather than 6. It's not that important, just a small nitpick.


+    u32 num_hws;
+
+    /* lane and orientation settings */
+    u8 lane_cnt;
+    u8 orientation;
+
+    /* COM PHY settings */
+    u32 hsclk_sel;
+    u32 dec_start_mode0;
+    u32 div_frac_start1_mode0;
+    u32 div_frac_start2_mode0;
+    u32 div_frac_start3_mode0;
+    u32 integloop_gain0_mode0;
+    u32 integloop_gain1_mode0;
+    u32 vco_tune_map;
+    u32 lock_cmp1_mode0;
+    u32 lock_cmp2_mode0;
+    u32 lock_cmp3_mode0;
+    u32 lock_cmp_en;
+
+    /* PHY vco divider */
+    u32 phy_vco_div;
+    /*
+     * Certain pll's needs to update the same vco rate after resume in
+     * suspend/resume scenario. Cached the vco rate for such plls.
+     */
+    unsigned long    vco_cached_rate;
+    u32        cached_cfg0;
+    u32        cached_cfg1;
+    u32        cached_outdiv;
+
+    uint32_t index;
+};
+
+static inline struct dp_pll_vco_clk *to_dp_vco_hw(struct clk_hw *hw)
+{
+    return container_of(hw, struct dp_pll_vco_clk, hw);
+}
+
+#define to_msm_dp_pll(vco) ((struct msm_dp_pll *)vco->priv)
+
+#define to_dp_pll_db(x)    ((struct dp_pll_db *)x->priv)
+
+int dp_vco_set_rate_10nm(struct clk_hw *hw, unsigned long rate,
+                unsigned long parent_rate);
+unsigned long dp_vco_recalc_rate_10nm(struct clk_hw *hw,
+                unsigned long parent_rate);
+long dp_vco_round_rate_10nm(struct clk_hw *hw, unsigned long rate,
+                unsigned long *parent_rate);
+int dp_vco_prepare_10nm(struct clk_hw *hw);
+void dp_vco_unprepare_10nm(struct clk_hw *hw);
+
+int msm_dp_pll_10nm_init(struct msm_dp_pll *dp_pll, int id);
+void msm_dp_pll_10nm_deinit(struct msm_dp_pll *dp_pll);

These functions don't seem to be used outside of dp_pll_10nm. What
about making them static?

I can't declare static to "init" and "deinit" as they are exported to dp_pll.c.
Rest of them I can move to dp_pll_10nm and then define static.

Please exuse me for not being exact enough. Of course I meant dp_vco_FOO_10nm() functions, not init/exit.

BTW: as I'm looking onto 7nm dp pll, which naming would you prefer?

We can have separate DP_PLL_10nm/DP_PLL_7nm namespaces (as DSI PLLs do) or I can override only a set of constants (like downstream driver does).

--
With best wishes
Dmitry