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Date: Sun, 28 Oct 2018 16:04:55 +0530
From: Taniya Das <tdas@...eaurora.org>
To: Stephen Boyd <sboyd@...nel.org>,
Michael Turquette <mturquette@...libre.com>
Cc: Andy Gross <andy.gross@...aro.org>,
David Brown <david.brown@...aro.org>,
Rajendra Nayak <rnayak@...eaurora.org>,
linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
chandanu@...eaurora.org, linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH v1 2/2] clk: qcom : dispcc: Add support for display port
clocks
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,
>>> + },
>>> + },
>>> +};
>>> +
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