linux-kernel - Re: [PATCH 06/20] interconnect: qcom: icc-rpm: Allow negative QoS offset

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Message-ID: <8983fc5f-b75e-3f38-577f-3c588acbe3f7@linaro.org>
Date:   Thu, 1 Jun 2023 12:56:14 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Georgi Djakov <djakov@...nel.org>,
        Leo Yan <leo.yan@...aro.org>, Evan Green <evgreen@...omium.org>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 06/20] interconnect: qcom: icc-rpm: Allow negative QoS
 offset

On 30/05/2023 13:20, Konrad Dybcio wrote:
> In some very very very very unfortunate cases, the correct offset of
> the QoS registers will be.. negative. One such case is MSM8998, where
> The DDR BWMON occupies what-would-be-the-BIMC-base which we usually
> take into account with the register calculation, making the actual
> BIMC node start at what-would-be-the-BIMC-base+0x300.

Can we turn one of devices into a child of another device? This way we 
won't have to cope with negative offsets.

> 
> In order to keep the calculation code sane, the simplest - however
> ugly it may be - solution is to allow the offset to be negative.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>   drivers/interconnect/qcom/icc-rpm.h | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpm.h b/drivers/interconnect/qcom/icc-rpm.h
> index d2c04c400cad..ba840a436cc0 100644
> --- a/drivers/interconnect/qcom/icc-rpm.h
> +++ b/drivers/interconnect/qcom/icc-rpm.h
> @@ -29,10 +29,10 @@ enum qcom_icc_type {
>    * @num_intf_clks: the total number of intf_clks clk_bulk_data entries
>    * @type: the ICC provider type
>    * @regmap: regmap for QoS registers read/write access
> - * @qos_offset: offset to QoS registers
>    * @bus_clk_rate: bus clock rate in Hz
>    * @bus_clks: the clk_bulk_data table of bus clocks
>    * @intf_clks: a clk_bulk_data array of interface clocks
> + * @qos_offset: offset to QoS registers

This can be kept in place.

>    * @keep_alive: whether to always keep a minimum vote on the bus clocks
>    * @is_on: whether the bus is powered on
>    */
> @@ -42,7 +42,7 @@ struct qcom_icc_provider {
>   	int num_intf_clks;
>   	enum qcom_icc_type type;
>   	struct regmap *regmap;
> -	unsigned int qos_offset;
> +	int qos_offset;
>   	u64 bus_clk_rate[NUM_BUS_CLKS];
>   	struct clk_bulk_data bus_clks[NUM_BUS_CLKS];
>   	struct clk_bulk_data *intf_clks;
> @@ -108,7 +108,7 @@ struct qcom_icc_desc {
>   	bool no_clk_scaling;
>   	enum qcom_icc_type type;
>   	const struct regmap_config *regmap_cfg;
> -	unsigned int qos_offset;
> +	int qos_offset;
>   };
>   
>   /* Valid for all bus types */
> 

-- 
With best wishes
Dmitry