linux-kernel - Re: [PATCH -next] drm/amd/display: Add a conversion function for transmitter and phy

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Date:   Wed, 30 Oct 2019 12:33:11 +0000
From:   "Kazlauskas, Nicholas" <Nicholas.Kazlauskas@....com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        "Wentland, Harry" <Harry.Wentland@....com>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "Zhou, David(ChunMing)" <David1.Zhou@....com>
CC:     "Li, Roman" <Roman.Li@....com>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "clang-built-linux@...glegroups.com" 
        <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH -next] drm/amd/display: Add a conversion function for
 transmitter and phy_id enums

On 2019-10-30 2:04 a.m., Nathan Chancellor wrote:
> Clang warns:
> 
> ../drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_link.c:2520:42:
> error: implicit conversion from enumeration type 'enum transmitter' to
> different enumeration type 'enum physical_phy_id'
> [-Werror,-Wenum-conversion]
>          psr_context->smuPhyId = link->link_enc->transmitter;
>                                ~ ~~~~~~~~~~~~~~~~^~~~~~~~~~~
> 1 error generated.
> 
> As the comment above this assignment states, this is intentional. To
> match previous warnings of this nature, add a conversion function that
> explicitly converts between the enums and warns when there is a
> mismatch.
> 
> See commit 828cfa29093f ("drm/amdgpu: Fix amdgpu ras to ta enums
> conversion") and commit d9ec5cfd5a2e ("drm/amd/display: Use switch table
> for dc_to_smu_clock_type") for previous examples of this.
> 
> Fixes: e0d08a40a63b ("drm/amd/display: Add debugfs entry for reading psr state")
> Link: https://github.com/ClangBuiltLinux/linux/issues/758
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@....com>

With the small nitpick that maybe the default case should be 
PHYLD_UNKNOWN, but well get the warning if that happens anyway.

Nicholas Kazlauskas

> ---
>   drivers/gpu/drm/amd/display/dc/core/dc_link.c | 38 ++++++++++++++++++-
>   1 file changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> index 7b18087be585..38dfe460e13b 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> @@ -2447,6 +2447,41 @@ bool dc_link_get_psr_state(const struct dc_link *link, uint32_t *psr_state)
>   	return true;
>   }
>   
> +static inline enum physical_phy_id
> +transmitter_to_phy_id(enum transmitter transmitter_value)
> +{
> +	switch (transmitter_value) {
> +	case TRANSMITTER_UNIPHY_A:
> +		return PHYLD_0;
> +	case TRANSMITTER_UNIPHY_B:
> +		return PHYLD_1;
> +	case TRANSMITTER_UNIPHY_C:
> +		return PHYLD_2;
> +	case TRANSMITTER_UNIPHY_D:
> +		return PHYLD_3;
> +	case TRANSMITTER_UNIPHY_E:
> +		return PHYLD_4;
> +	case TRANSMITTER_UNIPHY_F:
> +		return PHYLD_5;
> +	case TRANSMITTER_NUTMEG_CRT:
> +		return PHYLD_6;
> +	case TRANSMITTER_TRAVIS_CRT:
> +		return PHYLD_7;
> +	case TRANSMITTER_TRAVIS_LCD:
> +		return PHYLD_8;
> +	case TRANSMITTER_UNIPHY_G:
> +		return PHYLD_9;
> +	case TRANSMITTER_COUNT:
> +		return PHYLD_COUNT;
> +	case TRANSMITTER_UNKNOWN:
> +		return PHYLD_UNKNOWN;
> +	default:
> +		WARN_ONCE(1, "Unknown transmitter value %d\n",
> +			  transmitter_value);
> +		return PHYLD_0;
> +	}
> +}
> +
>   bool dc_link_setup_psr(struct dc_link *link,
>   		const struct dc_stream_state *stream, struct psr_config *psr_config,
>   		struct psr_context *psr_context)
> @@ -2517,7 +2552,8 @@ bool dc_link_setup_psr(struct dc_link *link,
>   	/* Hardcoded for now.  Can be Pcie or Uniphy (or Unknown)*/
>   	psr_context->phyType = PHY_TYPE_UNIPHY;
>   	/*PhyId is associated with the transmitter id*/
> -	psr_context->smuPhyId = link->link_enc->transmitter;
> +	psr_context->smuPhyId =
> +		transmitter_to_phy_id(link->link_enc->transmitter);
>   
>   	psr_context->crtcTimingVerticalTotal = stream->timing.v_total;
>   	psr_context->vsyncRateHz = div64_u64(div64_u64((stream->
>