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Subject: Re: [PATCH] misc: fastrpc: Update number of max fastrpc sessions
To:     Greg KH <gregkh@linuxfoundation.org>, Jeya R <jeyr@codeaurora.org>
Cc:     linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        fastrpc.upstream@qti.qualcomm.com
References: <1632123274-32054-1-git-send-email-jeyr@codeaurora.org>
 <YUg9dmThHg9s8XAy@kroah.com>
From:   Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Message-ID: <88370a7c-9e28-ae1b-2f48-bc38a8cff78f@linaro.org>
Date:   Mon, 20 Sep 2021 13:53:39 +0100
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On 20/09/2021 08:51, Greg KH wrote:
> On Mon, Sep 20, 2021 at 01:04:34PM +0530, Jeya R wrote:
>> For latest chipsets, upto 13 fastrpc sessions can be
>> supported. This includes 12 compute sessions and 1 cpz
>> session. Not updating this might result to out of bounds
>> memory access issues if more than 9 context bank nodes
>> are added to the DT file.
>>
>> Signed-off-by: Jeya R <jeyr@codeaurora.org>
>> ---
>>   drivers/misc/fastrpc.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
>> index beda610..bd7811e 100644
>> --- a/drivers/misc/fastrpc.c
>> +++ b/drivers/misc/fastrpc.c
>> @@ -24,7 +24,7 @@
>>   #define SDSP_DOMAIN_ID (2)
>>   #define CDSP_DOMAIN_ID (3)
>>   #define FASTRPC_DEV_MAX		4 /* adsp, mdsp, slpi, cdsp*/
>> -#define FASTRPC_MAX_SESSIONS	9 /*8 compute, 1 cpz*/
>> +#define FASTRPC_MAX_SESSIONS	13 /*12 compute, 1 cpz*/
>>   #define FASTRPC_ALIGN		128
>>   #define FASTRPC_MAX_FDLIST	16
>>   #define FASTRPC_MAX_CRCLIST	64
>> -- 
>> 2.7.4
>>
> 
> What happens if you run this on "older" chipsets?

This change should not have any implications on the older chips, as the 
existing compute context bank device tree entries will not exceed 9.

> 
> And is this an issue now, or can this wait to 5.16-rc1?

We could wait take in 5.16-rc1, as its an enhancement to allow more 
compute context banks.

--srini
> 
> thanks,
> 
> greg k-h
>