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Subject: Re: [PATCH] remoteproc: qcom: Introduce Hexagon V5 based WCSS driver
To:     Bjorn Andersson <bjorn.andersson@linaro.org>,
        Vinod <vkoul@kernel.org>
Cc:     ohad@wizery.com, robh+dt@kernel.org, mark.rutland@arm.com,
        andy.gross@linaro.org, david.brown@linaro.org,
        linux-remoteproc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-soc@vger.kernel.org, sibis@codeaurora.org
References: <1528177361-8883-1-git-send-email-sricharan@codeaurora.org>
 <20180605061919.GQ16230@vkoul-mobl>
 <3a4c102b-7228-153a-c588-b1bf00291fa8@codeaurora.org>
 <20180606161733.GE510@tuxbook-pro> <20180607041134.GF16230@vkoul-mobl>
 <20180607042443.GK510@tuxbook-pro>
From:   Sricharan R <sricharan@codeaurora.org>
Message-ID: <d01d6819-3f95-0b65-1251-aead88fe86cc@codeaurora.org>
Date:   Thu, 7 Jun 2018 10:59:58 +0530
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Hi Bjorn,

On 6/7/2018 9:54 AM, Bjorn Andersson wrote:
> On Wed 06 Jun 21:11 PDT 2018, Vinod wrote:
> 
>> On 06-06-18, 09:17, Bjorn Andersson wrote:
>>> On Tue 05 Jun 05:56 PDT 2018, Sricharan R wrote:
>>>
>>>> Hi Vinod,
>>>>
>>>> On 6/5/2018 11:49 AM, Vinod wrote:
>>>>> On 05-06-18, 11:12, Sricharan R wrote:
>>>>>
>>>>>> +config QCOM_Q6V5_WCSS
>>>>>> +	tristate "Qualcomm Hexagon based WCSS Peripheral Image Loader"
>>>>>> +	depends on OF && ARCH_QCOM
>>>>>> +	depends on QCOM_SMEM
>>>>>> +	depends on RPMSG_QCOM_SMD || (COMPILE_TEST && RPMSG_QCOM_SMD=n)
>>>>>> +	depends on RPMSG_QCOM_GLINK_SMEM || RPMSG_QCOM_GLINK_SMEM=n
>>>>>
>>>>> Is there a reason why it depends on RPMSG_QCOM_GLINK_SMEM=n? What would
>>>>> happen if distro wants both this and RPMSG_QCOM_GLINK_SMEM
>>>>>
>>>
>>> It says that QCOM_Q6V5_WCSS either must have a compatible state (i.e.
>>> builtin vs builtin, module vs builtin, but not builtin vs module) or
>>> that it's disabled, in which case we will hit the stub functions in
>>> qcom_glink.h.
>>>
>>> I.e. this prevents QCOM_Q6V5_WCSS to be compiled builtin when
>>> RPMSG_QCOM_GLINK_SMEM is module, as this would give us both stubs and
>>> the module.
>>
>> IIUC, you want to have QCOM_Q6V5_WCSS and RPMSG_QCOM_GLINK_SMEM as
>> modules or builtin
>>
> 
> RPMSG_QCOM_SMD, RPMSG_QCOM_GLINK_SMEM and QCOM_Q6V5_WCSS are all
> tristate.
> 
>> So, wouldn't Kconfig syntax something like where we say:
>>         M if RPMSG_QCOM_GLINK_SMEM=m
>>         bool if RPMSG_QCOM_GLINK_SMEM=y
>>
> 
> If we ignore SMD for a while we have the following combinations:
> 
> glink/wcss
> y     y - valid
> y     m - valid
> y     n - valid
> m     y - link failure (invalid)
> m     m - valid
> m     n - valid
> n     y - valid (platform uses wcss, but not glink)
> n     m - valid (-----"-----)
> n     n - valid
> 
> So to distill this we have the two valid cases:
> module/no if RPMSG_QCOM_GLINK_SMEM=m
> yes/module/no if RPMSG_QCOM_GLINK_SMEM=y
> 
> and the way you express that in Kconfig is the somewhat awkward
> 
>   depends on RPMSG_QCOM_GLINK_SMEM || RPMSG_QCOM_GLINK_SMEM=n
> 

 ok, Having "depends on RPMSG_QCOM_GLINK_SMEM" takes care of the
 first 6 cases in the above list.

 But just was thinking that by allowing the last three combinations,
 there is a chance that some config that really needs GLINK_SMEM and WCSS,
 but selects only Q6V5_WCSS and misses to select GLINK_SMEM,
 would still built and make it non-functional, right ?

Regards,
 Sricharan

>> Which makes it clear that both these have to be same type?
>>
> 
> They don't have to be of the same type, only of a compatible type.
> 

-- 
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