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

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On 2020-08-15 04:45, Dmitry Baryshkov wrote:
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.

Ok got it. Sorry I didn't mean to nitpick here.

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

I didn't get this. Did you mean naming convention of functions and structure between
7nm and 10 nm? Could you point me where 7nm dp pll code is posted?

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).

Having separate namespace sounds good.




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