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

[Taniya Das <tdas@codeaurora.org>]

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,
>>> +               },
>>> +       },
>>> +};
>>> +