Re: [PATCH] drm/amd/display: fix empty debug macros

[Alex Deucher]

On Mon, Sep 20, 2021 at 8:16 AM Arnd Bergmann  wrote:
>
> From: Arnd Bergmann 
>
> Using an empty macro expansion as a conditional expression
> produces a W=1 warning:
>
> drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_aux.c: In function 
> 'dce_aux_transfer_with_retries':
> drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_aux.c:775:156: error: 
> suggest braces around empty body in an 'if' statement [-Werror=empty-body]
>   775 | 
> "dce_aux_transfer_with_retries: AUX_RET_SUCCESS: 
> AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER");
>   |   
>   
>^
> drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_aux.c:783:155: error: 
> suggest braces around empty body in an 'if' statement [-Werror=empty-body]
>   783 | 
> "dce_aux_transfer_with_retries: AUX_RET_SUCCESS: 
> AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK");
>   |   
>   
>   ^
>
> Expand it to "do { } while (0)" instead to make the expression
> more robust and avoid the warning.
>
> Fixes: 56aca2309301 ("drm/amd/display: Add AUX I2C tracing.")
> Signed-off-by: Arnd Bergmann 

Applied.  Thanks!

Alex

> ---
>  drivers/gpu/drm/amd/display/dc/dce/dce_aux.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c 
> b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
> index e14f99b4b0c3..3c3347341103 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
> @@ -42,7 +42,7 @@
>  #define DC_LOGGER \
> engine->ctx->logger
>
> -#define DC_TRACE_LEVEL_MESSAGE(...) /* do nothing */
> +#define DC_TRACE_LEVEL_MESSAGE(...) do { } while (0)
>  #define IS_DC_I2CAUX_LOGGING_ENABLED() (false)
>  #define LOG_FLAG_Error_I2cAux LOG_ERROR
>  #define LOG_FLAG_I2cAux_DceAux LOG_I2C_AUX
> @@ -76,7 +76,7 @@ enum {
>  #define DEFAULT_AUX_ENGINE_MULT   0
>  #define DEFAULT_AUX_ENGINE_LENGTH 69
>
> -#define DC_TRACE_LEVEL_MESSAGE(...) /* do nothing */
> +#define DC_TRACE_LEVEL_MESSAGE(...) do { } while (0)
>
>  static void release_engine(
> struct dce_aux *engine)
> --
> 2.29.2
>

[PATCH] drm/amd/display: fix empty debug macros

[Arnd Bergmann]

From: Arnd Bergmann 

Using an empty macro expansion as a conditional expression
produces a W=1 warning:

drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_aux.c: In function 
'dce_aux_transfer_with_retries':
drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_aux.c:775:156: error: suggest 
braces around empty body in an 'if' statement [-Werror=empty-body]
  775 | 
"dce_aux_transfer_with_retries: AUX_RET_SUCCESS: 
AUX_TRANSACTION_REPLY_I2C_OVER_AUX_DEFER");
  | 

   ^
drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_aux.c:783:155: error: suggest 
braces around empty body in an 'if' statement [-Werror=empty-body]
  783 | 
"dce_aux_transfer_with_retries: AUX_RET_SUCCESS: 
AUX_TRANSACTION_REPLY_I2C_OVER_AUX_NACK");
  | 

  ^

Expand it to "do { } while (0)" instead to make the expression
more robust and avoid the warning.

Fixes: 56aca2309301 ("drm/amd/display: Add AUX I2C tracing.")
Signed-off-by: Arnd Bergmann 
---
 drivers/gpu/drm/amd/display/dc/dce/dce_aux.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c 
b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
index e14f99b4b0c3..3c3347341103 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
@@ -42,7 +42,7 @@
 #define DC_LOGGER \
engine->ctx->logger
 
-#define DC_TRACE_LEVEL_MESSAGE(...) /* do nothing */
+#define DC_TRACE_LEVEL_MESSAGE(...) do { } while (0)
 #define IS_DC_I2CAUX_LOGGING_ENABLED() (false)
 #define LOG_FLAG_Error_I2cAux LOG_ERROR
 #define LOG_FLAG_I2cAux_DceAux LOG_I2C_AUX
@@ -76,7 +76,7 @@ enum {
 #define DEFAULT_AUX_ENGINE_MULT   0
 #define DEFAULT_AUX_ENGINE_LENGTH 69
 
-#define DC_TRACE_LEVEL_MESSAGE(...) /* do nothing */
+#define DC_TRACE_LEVEL_MESSAGE(...) do { } while (0)
 
 static void release_engine(
struct dce_aux *engine)
-- 
2.29.2