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

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Date:   Thu, 1 Jun 2023 13:01:44 +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 01/06/2023 12:59, Konrad Dybcio wrote:
> 
> 
> On 1.06.2023 11:56, Dmitry Baryshkov wrote:
>> 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.
> Let's try to get more insight how they're correlated, but that sounds
> like an option.. 8996 will need this as well..

Anyway, I think this commit should be moved closer to the actual use.

> 
> Konrad
>>
>>>
>>> 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