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Tue, 25 Feb 2025 07:37:32 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id hUYMGDxzvWdcbgAAD6G6ig (envelope-from ); Tue, 25 Feb 2025 07:37:32 +0000 Message-ID: <466c38c3-7f74-46db-8270-bebafacf0007@suse.de> Date: Tue, 25 Feb 2025 08:37:32 +0100 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 v4 1/2] drm/format-helper: Add conversion from XRGB8888 to BGR888 To: "andriy.shevchenko@linux.intel.com" , Aditya Garg Cc: "maarten.lankhorst@linux.intel.com" , "mripard@kernel.org" , "airlied@gmail.com" , "simona@ffwll.ch" , Kerem Karabay , Atharva Tiwari , Aun-Ali Zaidi , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" References: <03FA573F-6D01-40E8-A666-CEA17A917036@live.com> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNJ1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPsLAjgQTAQgAOAIb AwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftODH AAoJEGgNwR1TC3ojx1wH/0hKGWugiqDgLNXLRD/4TfHBEKmxIrmfu9Z5t7vwUKfwhFL6hqvo lXPJJKQpQ2z8+X2vZm/slsLn7J1yjrOsoJhKABDi+3QWWSGkaGwRJAdPVVyJMfJRNNNIKwVb U6B1BkX2XDKDGffF4TxlOpSQzdtNI/9gleOoUA8+jy8knnDYzjBNOZqLG2FuTdicBXblz0Mf vg41gd9kCwYXDnD91rJU8tzylXv03E75NCaTxTM+FBXPmsAVYQ4GYhhgFt8S2UWMoaaABLDe 7l5FdnLdDEcbmd8uLU2CaG4W2cLrUaI4jz2XbkcPQkqTQ3EB67hYkjiEE6Zy3ggOitiQGcqp j//OwE0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRHUE9eosYb T6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgTRjP+qbU6 3Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+RdhgATnWW GKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zbehDda8lv hFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r12+lqdsA EQEAAcLAdgQYAQgAIAIbDBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftOH6AAoJEGgNwR1T C3ojVSkIALpAPkIJPQoURPb1VWjh34l0HlglmYHvZszJWTXYwavHR8+k6Baa6H7ufXNQtThR yIxJrQLW6rV5lm7TjhffEhxVCn37+cg0zZ3j7zIsSS0rx/aMwi6VhFJA5hfn3T0TtrijKP4A SAQO9xD1Zk9/61JWk8OysuIh7MXkl0fxbRKWE93XeQBhIJHQfnc+YBLprdnxR446Sh8Wn/2D Ya8cavuWf2zrB6cZurs048xe0UbSW5AOSo4V9M0jzYI4nZqTmPxYyXbm30Kvmz0rYVRaitYJ 4kyYYMhuULvrJDMjZRvaNe52tkKAvMevcGdt38H4KSVXAylqyQOW5zvPc4/sq9c= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.30 X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.997]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com,live.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_EQ_ADDR_SOME(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_TO(0.00)[linux.intel.com,live.com]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux.intel.com,kernel.org,gmail.com,ffwll.ch,kodeit.net,vger.kernel.org,lists.freedesktop.org]; RCPT_COUNT_SEVEN(0.00)[11]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO X-Spam-Level: Hi Am 24.02.25 um 15:29 schrieb andriy.shevchenko@linux.intel.com: > On Mon, Feb 24, 2025 at 01:38:32PM +0000, Aditya Garg wrote: >> From: Kerem Karabay >> >> Add XRGB8888 emulation helper for devices that only support BGR888. > ... > >> +static void drm_fb_xrgb8888_to_bgr888_line(void *dbuf, const void *sbuf, unsigned int pixels) > Okay the xrgb8888 is the actual pixel format independently on > the CPU endianess. > >> +{ >> + u8 *dbuf8 = dbuf; >> + const __le32 *sbuf32 = sbuf; > But here we assume that sbuf is __le32. > And I think we may benefit from the __be32 there. No, please. XRGB is the logical order. The raw physical byte order for DRM formats is always* little endian, hence reversed from the logical one. sbuf points to raw memory and is therefore __le32. DRM-format byte order is impossible to understand, I know. But that code is correct. Best regards Thomas *) White lie: there's a DRM format flag signalling physical big endianess. That isn't the case here. So nothing here should ever indicate big endianess. > >> + unsigned int x; >> + u32 pix; >> + >> + for (x = 0; x < pixels; x++) { >> + pix = le32_to_cpu(sbuf32[x]); >> + /* write red-green-blue to output in little endianness */ >> + *dbuf8++ = (pix & 0x00ff0000) >> 16; >> + *dbuf8++ = (pix & 0x0000ff00) >> 8; >> + *dbuf8++ = (pix & 0x000000ff) >> 0; > pix = be32_to_cpu(sbuf[4 * x]) >> 8; > put_unaligned_le24(pix, &dbuf[3 * x]); > >> + } > Or, after all, this __le32 magic might be not needed at all. Wouldn't the below > be the equivalent > > static void drm_fb_xrgb8888_to_bgr888_line(void *dbuf, const void *sbuf, unsigned int pixels) > { > unsigned int x; > u32 pix; > > for (x = 0; x < pixels; x++) { > /* Read red-green-blue from input in big endianess and... */ > pix = get_unaligned_be24(sbuf + x * 4 + 1); > /* ...write it to output in little endianness. */ > put_unaligned_le24(pix, dbuf + x * 3); > } > } > > The comments can even be dropped as the code quite clear about what's going on. > >> +} > But it's up to you. I don't know which solution gives better code generation > either. > -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)