Re: [PATCH v5 12/36] PM / devfreq: tegra20: Use MC timings for building OPP table

Chanwoo Choi
2020-08-14T00:48:53Z

Hi Dmitry,

On 8/14/20 9:05 AM, Dmitry Osipenko wrote:
> The clk_round_rate() won't be usable for building OPP table once
> interconnect support will be added to the EMC driver because that CLK API
> function limits the rounded rate based on the clk rate that is imposed by
> active clk-users, and thus, the rounding won't work as expected if
> interconnect will set the minimum EMC clock rate before devfreq driver is
> loaded. The struct tegra_mc contains memory timings which could be used by
> the devfreq driver for building up OPP table instead of rounding clock
> rate, this patch implements this idea.
>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/devfreq/tegra20-devfreq.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/devfreq/tegra20-devfreq.c b/drivers/devfreq/tegra20-devfreq.c
> index 6469dc69c5e0..a985f24098f5 100644
> --- a/drivers/devfreq/tegra20-devfreq.c
> +++ b/drivers/devfreq/tegra20-devfreq.c
> @@ -123,8 +123,7 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
> {
> struct tegra_devfreq *tegra;
> struct tegra_mc *mc;
> - unsigned long max_rate;
> - unsigned long rate;
> + unsigned int i;
> int err;
>
> mc = tegra_get_memory_controller();
> @@ -135,6 +134,11 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
> return err;
> }
>
> + if (!mc->num_timings) {
> + dev_info(&pdev->dev, "memory controller has no timings\n");
> + return -ENODEV;
> + }
> +
> tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
> if (!tegra)
> return -ENOMEM;
> @@ -151,12 +155,8 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>
> tegra->regs = mc->regs;
>
> - max_rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
> -
> - for (rate = 0; rate <= max_rate; rate++) {
> - rate = clk_round_rate(tegra->emc_clock, rate);
> -
> - err = dev_pm_opp_add(&pdev->dev, rate, 0);
> + for (i = 0; i < mc->num_timings; i++) {
> + err = dev_pm_opp_add(&pdev->dev, mc->timings[i].rate, 0);
> if (err) {
> dev_err(&pdev->dev, "failed to add opp: %d\n", err);
> goto remove_opps;
>

Ackded-by: Chanwoo Choi <cw00.choi@samsung.com>

--
Best Regards,
Chanwoo Choi
Samsung Electronics