Re: [PATCH v1 2/2] clk: qcom : dispcc: Add support for display port clocks

From: Taniya Das
Date: Sun Oct 28 2018 - 06:48:01 EST

Hello Stephen,

On 2018-10-19 16:04, Taniya Das wrote:
Hello Stephen,

On 10/10/2018 2:04 AM, Stephen Boyd wrote:
Quoting Taniya Das (2018-10-09 06:57:47)
diff --git a/drivers/clk/qcom/dispcc-sdm845.c b/drivers/clk/qcom/dispcc-sdm845.c
index 0cc4909..6d3136a 100644
--- a/drivers/clk/qcom/dispcc-sdm845.c
+++ b/drivers/clk/qcom/dispcc-sdm845.c
@@ -128,6 +144,100 @@ enum {
},
};

+static const struct freq_tbl ftbl_disp_cc_mdss_dp_aux_clk_src[] = {
+ F(19200000, P_BI_TCXO, 1, 0, 0),
+ { }
+};
+
+static struct clk_rcg2 disp_cc_mdss_dp_aux_clk_src = {
+ .cmd_rcgr = 0x219c,
+ .mnd_width = 0,
+ .hid_width = 5,
+ .parent_map = disp_cc_parent_map_2,
+ .freq_tbl = ftbl_disp_cc_mdss_dp_aux_clk_src,
+ .clkr.hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_aux_clk_src",
+ .parent_names = disp_cc_parent_names_2,
+ .num_parents = 2,
+ .flags = CLK_SET_RATE_PARENT,
+ .ops = &clk_rcg2_ops,
+ },
+};
+
+static const struct freq_tbl ftbl_disp_cc_mdss_dp_crypto_clk_src[] = {
+ F(108000, P_DP_PHY_PLL_LINK_CLK, 3, 0, 0),
+ F(180000, P_DP_PHY_PLL_LINK_CLK, 3, 0, 0),
+ F(360000, P_DP_PHY_PLL_LINK_CLK, 3, 0, 0),
+ F(540000, P_DP_PHY_PLL_LINK_CLK, 3, 0, 0),
+ { }
+};
+
+static struct clk_rcg2 disp_cc_mdss_dp_crypto_clk_src = {
+ .cmd_rcgr = 0x2154,
+ .mnd_width = 0,
+ .hid_width = 5,
+ .parent_map = disp_cc_parent_map_1,
+ .freq_tbl = ftbl_disp_cc_mdss_dp_crypto_clk_src,
+ .clkr.hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_crypto_clk_src",
+ .parent_names = disp_cc_parent_names_1,
+ .num_parents = 4,
+ .flags = CLK_GET_RATE_NOCACHE,

Why?

+ .ops = &clk_rcg2_ops,
+ },
+};
+
+static const struct freq_tbl ftbl_disp_cc_mdss_dp_link_clk_src[] = {
+ F(162000, P_DP_PHY_PLL_LINK_CLK, 1, 0, 0),
+ F(270000, P_DP_PHY_PLL_LINK_CLK, 1, 0, 0),
+ F(540000, P_DP_PHY_PLL_LINK_CLK, 1, 0, 0),
+ F(810000, P_DP_PHY_PLL_LINK_CLK, 1, 0, 0),

Are these in kHz? They really look like it and that's bad. Why do we
need them at all? Just to make sure the display driver picks these exact
frequencies? It seems like we could just pass whatever number comes in
up to the parent and see what it can do.


Let me check back the reason we had to make this change.

We will need this flag since we reset/power-down the PLL every time we disconnect/connect the DP cable or during suspend/resume. Only with this flag, the calls to the PLL driver are properly called.


+ { }
+};
+
+static struct clk_rcg2 disp_cc_mdss_dp_link_clk_src = {
+ .cmd_rcgr = 0x2138,
+ .mnd_width = 0,
+ .hid_width = 5,
+ .parent_map = disp_cc_parent_map_1,
+ .freq_tbl = ftbl_disp_cc_mdss_dp_link_clk_src,
+ .clkr.hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_link_clk_src",
+ .parent_names = disp_cc_parent_names_1,
+ .num_parents = 4,
+ .flags = CLK_SET_RATE_PARENT,
+ .ops = &clk_rcg2_ops,
+ },
+};
+
+static struct clk_rcg2 disp_cc_mdss_dp_pixel1_clk_src = {
+ .cmd_rcgr = 0x2184,
+ .mnd_width = 16,
+ .hid_width = 5,
+ .parent_map = disp_cc_parent_map_1,
+ .clkr.hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_pixel1_clk_src",
+ .parent_names = disp_cc_parent_names_1,
+ .num_parents = 4,
+ .flags = CLK_SET_RATE_PARENT,
+ .ops = &clk_dp_ops,
+ },
+};
+
+static struct clk_rcg2 disp_cc_mdss_dp_pixel_clk_src = {
+ .cmd_rcgr = 0x216c,
+ .mnd_width = 16,
+ .hid_width = 5,
+ .parent_map = disp_cc_parent_map_1,
+ .clkr.hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_pixel_clk_src",
+ .parent_names = disp_cc_parent_names_1,
+ .num_parents = 4,
+ .flags = CLK_SET_RATE_PARENT,
+ .ops = &clk_dp_ops,
+ },
+};
+
static const struct freq_tbl ftbl_disp_cc_mdss_esc0_clk_src[] = {
F(19200000, P_BI_TCXO, 1, 0, 0),
{ }
@@ -391,6 +501,115 @@ enum {
},
};

+static struct clk_branch disp_cc_mdss_dp_aux_clk = {
+ .halt_reg = 0x2054,
+ .halt_check = BRANCH_HALT,
+ .clkr = {
+ .enable_reg = 0x2054,
+ .enable_mask = BIT(0),
+ .hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_aux_clk",
+ .parent_names = (const char *[]){
+ "disp_cc_mdss_dp_aux_clk_src",
+ },
+ .num_parents = 1,
+ .flags = CLK_SET_RATE_PARENT,
+ .ops = &clk_branch2_ops,
+ },
+ },
+};
+
+static struct clk_branch disp_cc_mdss_dp_crypto_clk = {
+ .halt_reg = 0x2048,
+ .halt_check = BRANCH_HALT,
+ .clkr = {
+ .enable_reg = 0x2048,
+ .enable_mask = BIT(0),
+ .hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_crypto_clk",
+ .parent_names = (const char *[]){
+ "disp_cc_mdss_dp_crypto_clk_src",
+ },
+ .num_parents = 1,
+ .flags = CLK_SET_RATE_PARENT,
+ .ops = &clk_branch2_ops,
+ },
+ },
+};
+
+static struct clk_branch disp_cc_mdss_dp_link_clk = {
+ .halt_reg = 0x2040,
+ .halt_check = BRANCH_HALT,
+ .clkr = {
+ .enable_reg = 0x2040,
+ .enable_mask = BIT(0),
+ .hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_link_clk",
+ .parent_names = (const char *[]){
+ "disp_cc_mdss_dp_link_clk_src",
+ },
+ .num_parents = 1,
+ .flags = CLK_SET_RATE_PARENT,
+ .ops = &clk_branch2_ops,
+ },
+ },
+};
+
+/* reset state of disp_cc_mdss_dp_link_div_clk_src divider is 0x3 (div 4) */

Not sure what this comment is for. But it's interesting nonetheless.

+static struct clk_branch disp_cc_mdss_dp_link_intf_clk = {
+ .halt_reg = 0x2044,
+ .halt_check = BRANCH_HALT,
+ .clkr = {
+ .enable_reg = 0x2044,
+ .enable_mask = BIT(0),
+ .hw.init = &(struct clk_init_data){
+ .name = "disp_cc_mdss_dp_link_intf_clk",
+ .parent_names = (const char *[]){
+ "disp_cc_mdss_dp_link_clk_src",
+ },
+ .num_parents = 1,
+ .flags = CLK_GET_RATE_NOCACHE,

Why?


It was a requirement, but let me get back on this too.

I had a discussion with the Display Port teams and below is the requirement,

This flag is required since we reset/power-down the PLL every time they
disconnect/connect the DP cable or during suspend/resume.
Only with this flag, the calls to the PLL driver properly.

+ .ops = &clk_branch2_ops,
+ },
+ },
+};
+