Re: [PATCH v2 2/2] drm/i915/icl: reverse uninit order

From: Imre Deak <imre.deak@intel.com>
To: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: intel-gfx@lists.freedesktop.org, Paulo Zanoni <paulo.r.zanoni@intel.com>
Subject: Re: [PATCH v2 2/2] drm/i915/icl: reverse uninit order
Date: Tue, 13 Nov 2018 15:19:06 +0200	[thread overview]
Message-ID: <20181113131906.GA15029@ideak-desk.fi.intel.com> (raw)
In-Reply-To: <20181113024503.28886-2-lucas.demarchi@intel.com>

On Mon, Nov 12, 2018 at 06:45:03PM -0800, Lucas De Marchi wrote:
> Bspec 21257 says "DDIA PHY is the comp master, so it must
> not be un-initialized if other combo PHYs are in use". Here
> we are shutting down all phys, so it's not strictly required.
> However let's be consistent on deinitializing things in the
> reversed order we initialized them.
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_combo_phy.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_combo_phy.c b/drivers/gpu/drm/i915/intel_combo_phy.c
> index 49f3a533860d..9c06be45b84e 100644
> --- a/drivers/gpu/drm/i915/intel_combo_phy.c
> +++ b/drivers/gpu/drm/i915/intel_combo_phy.c
> @@ -9,6 +9,12 @@
>  	for ((__port) = PORT_A; (__port) < I915_MAX_PORTS; (__port)++)	\
>  		for_each_if(intel_port_is_combophy(__dev_priv, __port))
>  
> +#define for_each_combo_port_rev(__dev_priv, __port) \
> +	for ((__port) = I915_MAX_PORTS - 1; \
> +	     (__port) >= PORT_A && (__port) < I915_MAX_PORTS; \
> +	     (__port)--) \

Heh, so 'enum port' is unsigned. Surely I would have get this right
only after seeing it fail with only the >= condition :) An
alternative:

	for ((__port) = I915_MAX_PORTS; (__port)-- > 0;)

or add a negative value, like INVALID_PORT=-1 to 'enum port', but we'd
need some user for that too. Either way:

Reviewed-by: Imre Deak <imre.deak@intel.com>

> +		for_each_if(intel_port_is_combophy(__dev_priv, __port))
> +
>  enum {
>  	PROCMON_0_85V_DOT_0,
>  	PROCMON_0_95V_DOT_0,
> @@ -232,7 +238,7 @@ void icl_combo_phys_uninit(struct drm_i915_private *dev_priv)
>  {
>  	enum port port;
>  
> -	for_each_combo_port(dev_priv, port) {
> +	for_each_combo_port_rev(dev_priv, port) {
>  		u32 val;
>  
>  		if (!icl_combo_phy_verify_state(dev_priv, port))
> -- 
> 2.19.1.1.g56c4683e68
> 
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