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([2a01:e0a:c:37e0:8998:e0cf:68cc:1b62]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4255d8ab960sm19681894f8f.13.2025.10.06.01.06.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Oct 2025 01:06:53 -0700 (PDT) Message-ID: Date: Mon, 6 Oct 2025 10:06:51 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] drm/draw: add drm_draw_can_convert_from_xrgb8888 To: Jani Nikula , Francesco Valla , Javier Martinez Canillas , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20251005-drm_draw_conv_check-v1-0-9c814d9362f6@valla.it> <20251005-drm_draw_conv_check-v1-1-9c814d9362f6@valla.it> Content-Language: en-US, fr From: Jocelyn Falempe In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/6/25 08:48, Jani Nikula wrote: > On Sun, 05 Oct 2025, Francesco Valla wrote: >> Add drm_draw_can_convert_from_xrgb8888() function that can be used to >> determine if a XRGB8888 color can be converted to the specified format. >> >> Signed-off-by: Francesco Valla >> --- >> drivers/gpu/drm/drm_draw.c | 84 +++++++++++++++++++++++++++---------- >> drivers/gpu/drm/drm_draw_internal.h | 2 + >> 2 files changed, 63 insertions(+), 23 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_draw.c b/drivers/gpu/drm/drm_draw.c >> index 9dc0408fbbeadbe8282a2d6b210e0bfb0672967f..2641026a103d3b28cab9f5d378604b0604520fe4 100644 >> --- a/drivers/gpu/drm/drm_draw.c >> +++ b/drivers/gpu/drm/drm_draw.c >> @@ -15,45 +15,83 @@ >> #include "drm_draw_internal.h" >> #include "drm_format_internal.h" >> >> -/** >> - * drm_draw_color_from_xrgb8888 - convert one pixel from xrgb8888 to the desired format >> - * @color: input color, in xrgb8888 format >> - * @format: output format >> - * >> - * Returns: >> - * Color in the format specified, casted to u32. >> - * Or 0 if the format is not supported. >> - */ >> -u32 drm_draw_color_from_xrgb8888(u32 color, u32 format) >> +static int __drm_draw_color_from_xrgb8888(u32 color, u32 format, u32 *out_color) > > Is there any reason to change the return value of this function and > return the result via out_color? It already returns 0 if the format is > not supported. If there's a reason, it needs to be in the commit > message. I think the problem is that 0, is also a valid color. Maybe it would be better to split it into 2 functions, and duplicate the switch case. ie: u32 drm_draw_color_from_xrgb8888(u32 color, u32 format) { switch(format) { case DRM_FORMAT_RGB565: return drm_pixel_xrgb8888_to_rgb565(color); .... bool drm_draw_can_convert_from_xrgb8888(u32 format) { switch(format) { case DRM_FORMAT_RGB565: return true; .... default: return false; I didn't do it this way, because there is a risk to add a format to only one of the switch. But after more thinking, that would be simpler overall. Best regards, -- Jocelyn > >> { >> switch (format) { >> case DRM_FORMAT_RGB565: >> - return drm_pixel_xrgb8888_to_rgb565(color); >> + *out_color = drm_pixel_xrgb8888_to_rgb565(color); >> + break; >> case DRM_FORMAT_RGBA5551: >> - return drm_pixel_xrgb8888_to_rgba5551(color); >> + *out_color = drm_pixel_xrgb8888_to_rgba5551(color); >> + break; >> case DRM_FORMAT_XRGB1555: >> - return drm_pixel_xrgb8888_to_xrgb1555(color); >> + *out_color = drm_pixel_xrgb8888_to_xrgb1555(color); >> + break; >> case DRM_FORMAT_ARGB1555: >> - return drm_pixel_xrgb8888_to_argb1555(color); >> + *out_color = drm_pixel_xrgb8888_to_argb1555(color); >> + break; >> case DRM_FORMAT_RGB888: >> + fallthrough; > > That's not necessary for back to back case labels. Please don't add it. > >> case DRM_FORMAT_XRGB8888: >> - return color; >> + *out_color = color; >> + break; >> case DRM_FORMAT_ARGB8888: >> - return drm_pixel_xrgb8888_to_argb8888(color); >> + *out_color = drm_pixel_xrgb8888_to_argb8888(color); >> + break; >> case DRM_FORMAT_XBGR8888: >> - return drm_pixel_xrgb8888_to_xbgr8888(color); >> + *out_color = drm_pixel_xrgb8888_to_xbgr8888(color); >> + break; >> case DRM_FORMAT_ABGR8888: >> - return drm_pixel_xrgb8888_to_abgr8888(color); >> + *out_color = drm_pixel_xrgb8888_to_abgr8888(color); >> + break; >> case DRM_FORMAT_XRGB2101010: >> - return drm_pixel_xrgb8888_to_xrgb2101010(color); >> + *out_color = drm_pixel_xrgb8888_to_xrgb2101010(color); >> + break; >> case DRM_FORMAT_ARGB2101010: >> - return drm_pixel_xrgb8888_to_argb2101010(color); >> + *out_color = drm_pixel_xrgb8888_to_argb2101010(color); >> + break; >> case DRM_FORMAT_ABGR2101010: >> - return drm_pixel_xrgb8888_to_abgr2101010(color); >> + *out_color = drm_pixel_xrgb8888_to_abgr2101010(color); >> + break; >> default: >> - WARN_ONCE(1, "Can't convert to %p4cc\n", &format); >> - return 0; >> + return -1; > > Please don't use -1 as a generic error code. -1 is -EPERM. > >> } >> + >> + return 0; >> +} >> + >> +/** >> + * drm_draw_can_convert_from_xrgb8888 - check if xrgb8888 can be converted to the desired format >> + * @format: format >> + * >> + * Returns: >> + * True if XRGB8888 can be converted to the specified format, false otherwise. >> + */ >> +bool drm_draw_can_convert_from_xrgb8888(u32 format) >> +{ >> + u32 out_color; >> + >> + return __drm_draw_color_from_xrgb8888(0, format, &out_color) == 0; >> +} >> +EXPORT_SYMBOL(drm_draw_can_convert_from_xrgb8888); >> + >> +/** >> + * drm_draw_color_from_xrgb8888 - convert one pixel from xrgb8888 to the desired format >> + * @color: input color, in xrgb8888 format >> + * @format: output format >> + * >> + * Returns: >> + * Color in the format specified, casted to u32. >> + * Or 0 if the format is not supported. >> + */ >> +u32 drm_draw_color_from_xrgb8888(u32 color, u32 format) >> +{ >> + u32 out_color = 0; >> + >> + if (__drm_draw_color_from_xrgb8888(color, format, &out_color)) >> + WARN_ONCE(1, "Can't convert to %p4cc\n", &format); >> + >> + return out_color; >> } >> EXPORT_SYMBOL(drm_draw_color_from_xrgb8888); >> >> diff --git a/drivers/gpu/drm/drm_draw_internal.h b/drivers/gpu/drm/drm_draw_internal.h >> index f121ee7339dc11537f677c833f0ee94fe0e799cd..2ab4cb341df94fc4173dd6f5e7a512bdcfa5e55c 100644 >> --- a/drivers/gpu/drm/drm_draw_internal.h >> +++ b/drivers/gpu/drm/drm_draw_internal.h >> @@ -24,6 +24,8 @@ static inline const u8 *drm_draw_get_char_bitmap(const struct font_desc *font, >> return font->data + (c * font->height) * font_pitch; >> } >> >> +bool drm_draw_can_convert_from_xrgb8888(u32 format); >> + >> u32 drm_draw_color_from_xrgb8888(u32 color, u32 format); >> >> void drm_draw_blit16(struct iosys_map *dmap, unsigned int dpitch, >