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SubjectRe: [PATCH 2/2] clk: qcom: Add display clock controller driver for SDM845
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Quoting Taniya Das (2018-06-13 02:18:59)
> Hello Stephen,
>
> Thanks for review.
>
> On 6/12/2018 1:25 PM, Stephen Boyd wrote:
> > Quoting Taniya Das (2018-06-04 00:56:25)
> >> diff --git a/drivers/clk/qcom/dispcc-sdm845.c b/drivers/clk/qcom/dispcc-sdm845.c
> >> new file mode 100644
> >> index 0000000..317ab33
> >> --- /dev/null
> >> +++ b/drivers/clk/qcom/dispcc-sdm845.c
>
> >> +#include "common.h"
> >> +#include "gdsc.h"
> >> +#include "reset.h"
> >> +
> >> +#define F(f, s, h, m, n) { (f), (s), (2 * (h) - 1), (m), (n) }
> >
> > We really need to move this into the header file.
> >
> > $ git grep '#define F(' -- drivers/clk/qcom/ | wc -l
> > 13
> >
> Sure, will move this in a header and submit the patch.

Thanks!

> >> +
> >> +static struct clk_alpha_pll disp_cc_pll0 = {
> >> + .offset = 0x0,
> >> + .regs = clk_alpha_pll_regs[CLK_ALPHA_PLL_TYPE_FABIA],
> >> + .clkr = {
> >> + .hw.init = &(struct clk_init_data){
> >> + .name = "disp_cc_pll0",
> >> + .parent_names = (const char *[]){ "bi_tcxo" },
> >> + .num_parents = 1,
> >> + .ops = &clk_alpha_pll_fabia_ops,
> >> + },
> >> + },
> >> +};
> > [...]
> >> +
> >> +static struct clk_rcg2 disp_cc_mdss_pclk0_clk_src = {
> >> + .cmd_rcgr = 0x2058,
> >> + .mnd_width = 8,
> >> + .hid_width = 5,
> >> + .parent_map = disp_cc_parent_map_4,
> >> + .clkr.hw.init = &(struct clk_init_data){
> >> + .name = "disp_cc_mdss_pclk0_clk_src",
> >> + .parent_names = disp_cc_parent_names_4,
> >> + .num_parents = 4,
> >> + .flags = CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE,
> >
> > Why is the nocache flag needed? Applies to all clks in this file.
> >
>
> This flag is required for all RCGs whose PLLs are controlled outside the
> clock controller. The display code would require the recalculated rate
> always.

That doesn't really answer the question. It seems to describe some sort
of problem with the PLL being controlled outside the clk controller/clk
framework. Please add more details and comments into the code here.

>
> >> + .ops = &clk_pixel_ops,
> >> + },
> >> +};
> >> +
> >> +static struct clk_rcg2 disp_cc_mdss_pclk1_clk_src = {
> >> + .cmd_rcgr = 0x2070,
> >> + .mnd_width = 8,
> >> + .hid_width = 5,
> >> + .parent_map = disp_cc_parent_map_4,
> >> + .clkr.hw.init = &(struct clk_init_data){
> > [...]
> >> +
> >> +static const struct regmap_config disp_cc_sdm845_regmap_config = {
> >> + .reg_bits = 32,
> >> + .reg_stride = 4,
> >> + .val_bits = 32,
> >> + .max_register = 0x10000,
> >
> > This seems arbitrarily large. List the actual end?
> >
> The actual end is larger than this :( , I have listed the range till the
> register offset are used here.

Ok.

>
> >> + .fast_io = true,
> >> +};
> >> +
> >> +static const struct qcom_cc_desc disp_cc_sdm845_desc = {
> >> + .config = &disp_cc_sdm845_regmap_config,
> >> + .clks = disp_cc_sdm845_clocks,
> >> + .num_clks = ARRAY_SIZE(disp_cc_sdm845_clocks),
> >> + .resets = disp_cc_sdm845_resets,
> >> + .num_resets = ARRAY_SIZE(disp_cc_sdm845_resets),
> >> + .gdscs = disp_cc_sdm845_gdscs,
> >> + .num_gdscs = ARRAY_SIZE(disp_cc_sdm845_gdscs),
> >> +};
> >> +
> >> +static const struct of_device_id disp_cc_sdm845_match_table[] = {
> >> + { .compatible = "qcom,sdm845-dispcc" },
> >> + { }
> >> +};
> >> +MODULE_DEVICE_TABLE(of, disp_cc_sdm845_match_table);
> >> +
> >> +static int disp_cc_sdm845_probe(struct platform_device *pdev)
> >> +{
> >> + struct regmap *regmap;
> >> +
> >> + regmap = qcom_cc_map(pdev, &disp_cc_sdm845_desc);
> >> + if (IS_ERR(regmap))
> >> + return PTR_ERR(regmap);
> >> +
> >> + clk_fabia_pll_configure(&disp_cc_pll0, regmap, &disp_cc_pll0_config);
> >> +
> >> + /* Enable clock gating for DSI and MDP clocks */
> >
> > Hardware clock gating? What does this mean.
> >
> These are used for deciding whether to enable HW based Clock gating or
> not. Setting these bit will enable HW based Clock gating.

Please state it's hardware clock gating then in the comment.

>
> >> + regmap_update_bits(regmap, 0x8000, 0x7f0, 0x7f0);
> >> +
> >> + return qcom_cc_really_probe(pdev, &disp_cc_sdm845_desc, regmap);
> >> +}
>

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