linux-kernel - RE: [PATCH v2 3/3] clocksource/drivers/exynos

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Date:   Sun, 20 Feb 2022 22:29:49 +0530
From:   "Alim Akhtar" <alim.akhtar@...sung.com>
To:     "'Krzysztof Kozlowski'" <krzysztof.kozlowski@...onical.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Cc:     <linux-samsung-soc@...r.kernel.org>, <daniel.lezcano@...aro.org>,
        <tglx@...utronix.de>, <pankaj.dubey@...sung.com>,
        <m.szyprowski@...sung.com>
Subject: RE: [PATCH v2 3/3] clocksource/drivers/exynos_mct: bump up number
 of local timer



>-----Original Message-----
>From: Krzysztof Kozlowski [mailto:krzysztof.kozlowski@...onical.com]
>Sent: Sunday, February 20, 2022 9:03 PM
>To: Alim Akhtar <alim.akhtar@...sung.com>; linux-arm-
>kernel@...ts.infradead.org; linux-kernel@...r.kernel.org
>Cc: linux-samsung-soc@...r.kernel.org; daniel.lezcano@...aro.org;
>tglx@...utronix.de; pankaj.dubey@...sung.com;
>m.szyprowski@...sung.com
>Subject: Re: [PATCH v2 3/3] clocksource/drivers/exynos_mct: bump up
>number of local timer
>
>On 20/02/2022 14:38, Alim Akhtar wrote:
>> As per the dt binding, maximum number of local timer can be up to 16.
>> Increase the array size of the _name_ variable which holds the number
>> of local timer name per CPU to reflect the binding. While at it,
>> change the magic number to a meaningful macro.
>
>This still does not make sense. Let's say you have 16 local timers, so why the
>name of clock event device should be maximum 16? How are these related?
>
As you rightly commented on v1 and it is mainly for "mct_tick%d" with number of local timers and
local timer is per cpu. With increase in cpu number, name[10] restrict the scalability.
So either we can change to 11, or use some reference (as local timer number in this patch). 
Let me know your thought on this.

>>
>> Signed-off-by: Alim Akhtar <alim.akhtar@...sung.com>
>> ---
>>  drivers/clocksource/exynos_mct.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clocksource/exynos_mct.c
>> b/drivers/clocksource/exynos_mct.c
>> index 0c7931f7f99a..8d63a9376701 100644
>> --- a/drivers/clocksource/exynos_mct.c
>> +++ b/drivers/clocksource/exynos_mct.c
>> @@ -66,6 +66,8 @@
>>  #define MCT_L0_IRQ	4
>>  /* Max number of IRQ as per DT binding document */
>>  #define MCT_NR_IRQS	20
>> +/* Max number of local timers */
>> +#define MCT_NR_LOCAL_TIMERS	16
>>
>>  enum {
>>  	MCT_INT_SPI,
>> @@ -80,7 +82,7 @@ static int mct_irqs[MCT_NR_IRQS];  struct
>> mct_clock_event_device {
>>  	struct clock_event_device evt;
>>  	unsigned long base;
>> -	char name[10];
>> +	char name[MCT_NR_LOCAL_TIMERS];
>>  };
>>
>>  static void exynos4_mct_write(unsigned int value, unsigned long
>> offset)
>
>
>Best regards,
>Krzysztof