linux-kernel - Re: [PATCH 3/7] drivers: soc: xilinx: add check for platform

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Message-ID: <68e8a5ad-650b-4d1b-94fa-8eb74e904aac@amd.com>
Date:   Mon, 2 Oct 2023 10:12:38 +0200
From:   Michal Simek <michal.simek@....com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     Jay Buddhabhatti <jay.buddhabhatti@....com>, <tanmay.shah@....com>,
        <sai.krishna.potthuri@....com>, <nava.kishore.manne@....com>,
        <ben.levinsky@....com>, <dhaval.r.shah@....com>, <marex@...x.de>,
        <robh@...nel.org>, <arnd@...db.de>, <izhar.ameer.shaikh@....com>,
        <ruanjinjie@...wei.com>, <mathieu.poirier@...aro.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/7] drivers: soc: xilinx: add check for platform



On 10/2/23 08:20, Greg KH wrote:
> On Mon, Oct 02, 2023 at 08:09:50AM +0200, Michal Simek wrote:
>>
>>
>> On 9/30/23 09:17, Greg KH wrote:
>>> On Fri, Sep 29, 2023 at 03:55:54AM -0700, Jay Buddhabhatti wrote:
>>>> Some error event IDs for Versal and Versal NET are different.
>>>> Both the platforms should access their respective error event
>>>> IDs so use sub_family_code to check for platform and check
>>>> error IDs for respective platforms. The family code is passed
>>>> via platform data to avoid platform detection again.
>>>> Platform data is setup when even driver is registered.
>>>>
>>>> Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@....com>
>>>> ---
>>>>    drivers/firmware/xilinx/zynqmp.c        |  2 +-
>>>>    drivers/soc/xilinx/xlnx_event_manager.c | 25 ++++++++++++++++++++-----
>>>>    include/linux/firmware/xlnx-zynqmp.h    | 16 ++++++++++++----
>>>>    3 files changed, 33 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
>>>> index 5f40288f69a9..6583efa9ac48 100644
>>>> --- a/drivers/firmware/xilinx/zynqmp.c
>>>> +++ b/drivers/firmware/xilinx/zynqmp.c
>>>> @@ -2019,7 +2019,7 @@ static int zynqmp_firmware_probe(struct platform_device *pdev)
>>>>    	np = of_find_compatible_node(NULL, NULL, "xlnx,versal");
>>>>    	if (np) {
>>>>    		em_dev = platform_device_register_data(&pdev->dev, "xlnx_event_manager",
>>>> -						       -1, NULL, 0);
>>>> +						       -1, &pm_sub_family_code, 4);
>>>>    		if (IS_ERR(em_dev))
>>>>    			dev_err_probe(&pdev->dev, PTR_ERR(em_dev), "EM register fail with error\n");
>>>>    	}
>>>> diff --git a/drivers/soc/xilinx/xlnx_event_manager.c b/drivers/soc/xilinx/xlnx_event_manager.c
>>>> index 38cfc161a713..8074ded7b39c 100644
>>>> --- a/drivers/soc/xilinx/xlnx_event_manager.c
>>>> +++ b/drivers/soc/xilinx/xlnx_event_manager.c
>>>> @@ -23,6 +23,7 @@ static DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number1);
>>>>    static int virq_sgi;
>>>>    static int event_manager_availability = -EACCES;
>>>> +static u32 pm_sub_family_code;
>>>
>>> Why is this not a per-device variable?  Global variables like this for
>>> drivers are almost always wrong.
>>
>> Not sure I get what you mean by per-device. Can you please elaborate on it?
> 
> It should not be a global variable (i.e. the same for all devices in the
> system.)

You are not changing silicon when you run OS. It means strictly speaking you are 
not changing sub family silicon code.


>> This is the part of firmware infrastructure and there is only one instance
>> of the driver in the system registered from firmware driver itself.
> 
> Then that should be fixed.
> 
>> If this should be done in a generic way then there are much more variables
>> which should be moved to driver data not just this one.
> 
> Agreed, they should all be moved there.

Let us to take a look at what can be done to try to remove all of them.

Jay: Can you please remove this patch from this series and let's deal with it 
separately?

Greg: Are you fine with others?

Thanks,
Michal