Re: [PATCH v4 2/4] interconnect: qcom: Add OSM L3 interconnect provider support

[Sibi Sankar <sibis@codeaurora.org>]

Hey Evan,

Thanks for the review!

On 2020-01-22 03:03, Evan Green wrote:
> On Thu, Jan 9, 2020 at 1:12 PM Sibi Sankar <sibis@codeaurora.org> 
> wrote:
>> 
>> On some Qualcomm SoCs, Operating State Manager (OSM) controls the
>> resources of scaling L3 caches. Add a driver to handle bandwidth
>> requests to OSM L3 from CPU on SDM845 SoCs.
>> 
>> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
>> ---
>>  drivers/interconnect/qcom/Kconfig  |   7 +
>>  drivers/interconnect/qcom/Makefile |   2 +
>>  drivers/interconnect/qcom/osm-l3.c | 267 
>> +++++++++++++++++++++++++++++
>>  3 files changed, 276 insertions(+)
>>  create mode 100644 drivers/interconnect/qcom/osm-l3.c
>> 
>> diff --git a/drivers/interconnect/qcom/Kconfig 
>> b/drivers/interconnect/qcom/Kconfig
>> index a9bbbdf7400f9..b94d28e7bf700 100644
>> --- a/drivers/interconnect/qcom/Kconfig
>> +++ b/drivers/interconnect/qcom/Kconfig
>> @@ -14,6 +14,13 @@ config INTERCONNECT_QCOM_MSM8974
>>          This is a driver for the Qualcomm Network-on-Chip on 
>> msm8974-based
>>          platforms.
>> 
>> +config INTERCONNECT_QCOM_OSM_L3
>> +       tristate "Qualcomm OSM L3 interconnect driver"
>> +       depends on INTERCONNECT_QCOM || COMPILE_TEST
>> +       help
>> +         Say y here to support the Operating State Manager (OSM) 
>> interconnect
>> +         driver which controls the scaling of L3 caches on Qualcomm 
>> SoCs.
>> +
>>  config INTERCONNECT_QCOM_QCS404
>>         tristate "Qualcomm QCS404 interconnect driver"
>>         depends on INTERCONNECT_QCOM
>> diff --git a/drivers/interconnect/qcom/Makefile 
>> b/drivers/interconnect/qcom/Makefile
>> index 55ec3c5c89dbd..89fecbd1257c7 100644
>> --- a/drivers/interconnect/qcom/Makefile
>> +++ b/drivers/interconnect/qcom/Makefile
>> @@ -1,5 +1,6 @@
>>  # SPDX-License-Identifier: GPL-2.0
>> 
>> +icc-osm-l3-objs                                := osm-l3.o
>>  qnoc-msm8974-objs                      := msm8974.o
>>  qnoc-qcs404-objs                       := qcs404.o
>>  qnoc-sc7180-objs                       := sc7180.o
>> @@ -12,6 +13,7 @@ icc-smd-rpm-objs                      := smd-rpm.o
>>  obj-$(CONFIG_INTERCONNECT_QCOM_BCM_VOTER) += icc-bcm-voter.o
>>  obj-$(CONFIG_INTERCONNECT_QCOM_MSM8916) += qnoc-msm8916.o
>>  obj-$(CONFIG_INTERCONNECT_QCOM_MSM8974) += qnoc-msm8974.o
>> +obj-$(CONFIG_INTERCONNECT_QCOM_OSM_L3) += icc-osm-l3.o
>>  obj-$(CONFIG_INTERCONNECT_QCOM_QCS404) += qnoc-qcs404.o
>>  obj-$(CONFIG_INTERCONNECT_QCOM_RPMH) += icc-rpmh.o
>>  obj-$(CONFIG_INTERCONNECT_QCOM_SC7180) += qnoc-sc7180.o
>> diff --git a/drivers/interconnect/qcom/osm-l3.c 
>> b/drivers/interconnect/qcom/osm-l3.c
>> new file mode 100644
>> index 0000000000000..7fde53c70081e
>> --- /dev/null
>> +++ b/drivers/interconnect/qcom/osm-l3.c
>> @@ -0,0 +1,267 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
>> + *
>> + */
>> +
>> +#include <dt-bindings/interconnect/qcom,osm-l3.h>
>> +#include <linux/bitfield.h>
>> +#include <linux/clk.h>
>> +#include <linux/interconnect-provider.h>
>> +#include <linux/io.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define LUT_MAX_ENTRIES                        40U
>> +#define LUT_SRC                                GENMASK(31, 30)
>> +#define LUT_L_VAL                      GENMASK(7, 0)
>> +#define LUT_ROW_SIZE                   32
>> +#define CLK_HW_DIV                     2
>> +
>> +/* Register offsets */
>> +#define REG_ENABLE                     0x0
>> +#define REG_FREQ_LUT                   0x110
>> +#define REG_PERF_STATE                 0x920
>> +
>> +#define OSM_L3_MAX_LINKS               1
>> +#define SDM845_MAX_RSC_NODES           130
> 
> I'm nervous this define is going to fall out of date with
> qcom,sdm845.h. I'm worried someone will end up adding a few more nodes
> that were always there but previously hidden from Linux. Can we put
> this define in include/dt-bindings/interconnect/qcom,sdm845.h, so at
> least when that happens they'll come face to face with this define?
> The same comment goes for the SC7180 define in patch 4.

Yeah both solution require manual
intervention how about we just go
with what I proposed below.

> 
> On second thought, this trick only works once. Are we sure there
> aren't going to be other drivers that might want to tag on
> interconnect nodes as well? How about instead we just add the enum
> values below in qcom,sdm845.h as defines?

Georgi/Evan,
Since qcom,sdm845.h is specific to
bindings shouldn't I just create a
.h file with all the enums so that
it can used across all icc providers
on SDM845?

> 
> -Evan

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