linux-kernel - Re: [PATCH 3/4] bus: tegra-aconnect: make it explicitly non-modular

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Message-ID: <577A68EE.3040402@nvidia.com>
Date:	Mon, 4 Jul 2016 14:47:26 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
CC:	<linux-kernel@...r.kernel.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	<linux-tegra@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/4] bus: tegra-aconnect: make it explicitly non-modular


On 04/07/16 14:41, Paul Gortmaker wrote:
> [Re: [PATCH 3/4] bus: tegra-aconnect: make it explicitly non-modular] On 04/07/2016 (Mon 10:17) Jon Hunter wrote:
> 
>> Hi Paul,
>>
>> On 03/07/16 18:30, Paul Gortmaker wrote:
>>> The Kconfig currently controlling compilation of this code is:
>>>
>>> drivers/bus/Kconfig:config TEGRA_ACONNECT
>>> drivers/bus/Kconfig:    bool "Tegra ACONNECT Bus Driver"
>>>
>>> ...meaning that it currently is not being built as a module by anyone.
>>>
>>> Lets remove the modular code that is essentially orphaned, so that
>>> when reading the driver there is no doubt it is builtin-only.
>>>
>>> We explicitly disallow a driver unbind, since that doesn't have a
>>> sensible use case anyway, and it allows us to drop the ".remove"
>>> code for non-modular drivers.
>>>
>>> Since module_platform_driver() uses the same init level priority as
>>> builtin_platform_driver() the init ordering remains unchanged with
>>> this commit.
>>>
>>> Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
>>>
>>> We also delete the MODULE_LICENSE tag etc. since all that information
>>> was (or is now) contained at the top of the file in the comments.
>>
>> In version 3 of the aconnect series [0] I had made this a tristate
>> because we allowed it to be removed and you had submitted a patch to
>> export the PM_CLK APIs. However, when discussing with Thierry he said
>> that we were unable to merge with tristate because of the dependency on
>> your patch. So he suggested we merge with bool for now and then change
>> it back to tristate for v4.9.
> 
> Oh I see.  The exported clock syms were for the 210 DMA driver and it
> never crossed my mind that this driver needed the same syms in order for
> it to be tristate.  Guess the exports proved useful afterall.  :)

Yes indeed and I did learn my lesson after your previous catch for the
ADMA ;-)

>>
>> I understand that we should not do this, but we do plan to make this
>> modular in the future.
> 
> No problem ; I will drop this patch in favor of a one line Kconfig patch
> in my test queue so it doesn't trip the regular audit, just like I have
> for the 210 below -- not yet submitted for the same dependency reason.
> 
> P.
> ---
> 
> 
>  From fe5bdc6348828c157deb14e8d75c732abcc2ad2b Mon Sep 17 00:00:00 2001
> From: Paul Gortmaker <paul.gortmaker@...driver.com>
> Date: Fri, 20 May 2016 14:30:43 -0400
> Subject: [PATCH] dma: tegra210-adma: convert TEGRA210_ADMA from bool to
>  tristate
> 
> This driver currently uses modular infrastructure but is controlled
> by a bool Kconfig.
> 
> There is a general consensus from the DMA reviewers and maintainers
> that "if it can be modular, it should be modular" in order to keep
> the bzImage size under control for multi platform kernels.
> 
> Build tested only.  Also needs some new pm_clk symbols exported
> before this commit is applied to tree in order to avoid modpost
> errors like:
> 
>   ERROR: "pm_clk_add_clk" [drivers/dma/tegra210-adma.ko] undefined!
>   ERROR: "pm_clk_create" [drivers/dma/tegra210-adma.ko] undefined!
>   ERROR: "pm_clk_destroy" [drivers/dma/tegra210-adma.ko] undefined!
>   ERROR: "pm_clk_suspend" [drivers/dma/tegra210-adma.ko] undefined!
>   ERROR: "pm_clk_resume" [drivers/dma/tegra210-adma.ko] undefined!
> 
> Cc: Laxman Dewangan <ldewangan@...dia.com>
> Cc: Jon Hunter <jonathanh@...dia.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Vinod Koul <vinod.koul@...el.com>
> Cc: Stephen Warren <swarren@...dotorg.org>
> Cc: Thierry Reding <thierry.reding@...il.com>
> Cc: Alexandre Courbot <gnurou@...il.com>
> Cc: dmaengine@...r.kernel.org
> Cc: linux-tegra@...r.kernel.org
> Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
> ---
>  drivers/dma/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 8c98779a12b1..866068d84ca2 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -468,7 +468,7 @@ config TEGRA20_APB_DMA
>  	  or vice versa. It does not support memory to memory data transfer.
>  
>  config TEGRA210_ADMA
> -	bool "NVIDIA Tegra210 ADMA support"
> +	tristate "NVIDIA Tegra210 ADMA support"
>  	depends on ARCH_TEGRA_210_SOC
>  	select DMA_ENGINE
>  	select DMA_VIRTUAL_CHANNELS

Thanks! FWIW ...

Acked-by: Jon Hunter <jonathanh@...dia.com>

Cheers
Jon

-- 
nvpublic