linux-kernel - Re: [PATCH 3/3] clk: qcom: dispcc-sm8750: Add SM8750 Display clock controller

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Message-ID: <ef6f9bd0-c24b-4964-9228-bdab1221fff5@linaro.org>
Date: Wed, 4 Dec 2024 11:05:38 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Stephen Boyd <sboyd@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Michael Turquette <mturquette@...libre.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Rob Herring <robh@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] clk: qcom: dispcc-sm8750: Add SM8750 Display clock
 controller

On 03/12/2024 23:09, Stephen Boyd wrote:
> Quoting Krzysztof Kozlowski (2024-11-28 07:08:01)
>> diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
>> index 2ec9be21ff678e3343cccafa85801aa68805f440..d9ab42c625ddd61f9bf1857522d44d4547e42bf5 100644
>> --- a/drivers/clk/qcom/Kconfig
>> +++ b/drivers/clk/qcom/Kconfig
>> @@ -1022,6 +1022,16 @@ config SM_DISPCC_8550
>>           Say Y if you want to support display devices and functionality such as
>>           splash screen.
>>  
>> +config SM_DISPCC_8750
>> +       tristate "SM8750 Display Clock Controller"
>> +       depends on ARM64 || COMPILE_TEST
> 
> Please select QCOM_GDSC

Ack

> 
>> +       depends on SM_GCC_8750
> 
> select? Or imply? It's a functional dependency, not a build time one.

ARM64 is as well functional dependency, ARCH_QCOM present in all other
drivers as well. It is all the same. The point is to limit the config
options available to users/distros when they do not need them. In this
particular case: if user does not select main clock controller (GCC)
then allowing to choose Display clock controller is pointless.

> 
>> +       help
>> diff --git a/drivers/clk/qcom/dispcc-sm8750.c b/drivers/clk/qcom/dispcc-sm8750.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..ff64ff93c4dbdd2aae22b55dd0e404544cc9373e
>> --- /dev/null
>> +++ b/drivers/clk/qcom/dispcc-sm8750.c
>> @@ -0,0 +1,1960 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2021, The Linux Foundation. All rights reserved.
>> + * Copyright (c) 2023-2024, Linaro Ltd.
>> + */
>> +
>> +#include <linux/clk.h>
> 
> Is this include used?

Not used, copy pasta from older driver. I'll clean it up.

> 
>> +#include <linux/clk-provider.h>
>> +#include <linux/err.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +#include <linux/pm_runtime.h>
>> +
>> +#include <dt-bindings/clock/qcom,sm8750-dispcc.h>
>> +
>> +#include "common.h"
>> +#include "clk-alpha-pll.h"
>> +#include "clk-branch.h"
>> +#include "clk-pll.h"
>> +#include "clk-rcg.h"
>> +#include "clk-regmap.h"
>> +#include "clk-regmap-divider.h"
>> +#include "clk-regmap-mux.h"
>> +#include "reset.h"
>> +#include "gdsc.h"
> [...]
>> +};
>> +
>> +static struct clk_rcg2 disp_cc_mdss_mdp_clk_src = {
>> +       .cmd_rcgr = 0x8150,
>> +       .mnd_width = 0,
>> +       .hid_width = 5,
>> +       .parent_map = disp_cc_parent_map_9,
>> +       .freq_tbl = ftbl_disp_cc_mdss_mdp_clk_src,
>> +       .clkr.hw.init = &(const struct clk_init_data) {
>> +               .name = "disp_cc_mdss_mdp_clk_src",
>> +               .parent_data = disp_cc_parent_data_9,
>> +               .num_parents = ARRAY_SIZE(disp_cc_parent_data_9),
>> +               .flags = CLK_SET_RATE_PARENT,
>> +               .ops = &clk_rcg2_shared_ops, /* TODO: switch to cesta managed clocks */
> 
> What is cesta?

Cesta is a new hardware block which receives votes from consumers and
then manages groups of clocks. We do not have drivers for it, so I am
not sure how this here will work out.

I will grow the explanation in comment.

> 
>> +       },
>> +};
>> +
>> +static struct clk_rcg2 disp_cc_mdss_pclk0_clk_src = {
>> +       .cmd_rcgr = 0x8108,
>> +       .mnd_width = 8,
>> +       .hid_width = 5,
>> +       .parent_map = disp_cc_parent_map_1,
>> +       .freq_tbl = ftbl_disp_cc_esync0_clk_src,
>> +       .clkr.hw.init = &(const struct clk_init_data) {
>> +               .name = "disp_cc_mdss_pclk0_clk_src",
>> +               .parent_data = disp_cc_parent_data_1,
>> +               .num_parents = ARRAY_SIZE(disp_cc_parent_data_1),
>> +               .flags = CLK_SET_RATE_PARENT,
>> +               .ops = &clk_pixel_ops,
>> +       },
> [...]
>> +               .enable_reg = 0x80b4,
>> +               .enable_mask = BIT(0),
>> +               .hw.init = &(const struct clk_init_data) {
>> +                       .name = "disp_cc_osc_clk",
>> +                       .parent_hws = (const struct clk_hw*[]) {
>> +                               &disp_cc_osc_clk_src.clkr.hw,
>> +                       },
>> +                       .num_parents = 1,
>> +                       .flags = CLK_SET_RATE_PARENT,
>> +                       .ops = &clk_branch2_ops,
>> +               },
>> +       },
>> +};
>> +
>> +static struct gdsc mdss_gdsc = {
>> +       .gdscr = 0x9000,
>> +       .en_rest_wait_val = 0x2,
>> +       .en_few_wait_val = 0x2,
>> +       .clk_dis_wait_val = 0xf,
>> +       .pd = {
>> +               .name = "mdss_gdsc",
>> +       },
>> +       .pwrsts = PWRSTS_OFF_ON,
>> +       .flags = POLL_CFG_GDSCR | HW_CTRL | RETAIN_FF_ENABLE,
>> +       // TODO: no supply?
> 
> What is this?

Development note. I will clean it up.



Best regards,
Krzysztof