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RCPT_COUNT_SEVEN(0.00)[7]; DKIM_TRACE(0.00)[suse.de:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:email,suse.de:dkim,suse.com:url] X-Spam-Flag: NO X-Spam-Score: -4.50 Hi Am 13.10.26 um 15:07 schrieb Jie Feng: > On Tue, 13 Oct 2026 at 20:32, Thomas Zimmermann wrote: >> Hi >> >> Am 13.10.26 um 14:17 schrieb Jie Feng: >>> On Tue, 13 Oct 2026 at 15:11, Thomas Zimmermann wrote: >>>> Hi >>>> >>>> Am 12.10.26 um 19:08 schrieb Ho Jie Feng: >>>>> Add a helper for devices that use packed UYVY but accept XRGB8888 >>>>> framebuffers. >>>> Is there a description of UYVY available somewhere? >>> This is for a reverse engineered usb display adapter, which accepts >>> input in bytes of U, Y, V, Y in that order. I'm not sure what >>> counts as a description, apart from it matching DRM_FORMAT_UYVY? >> I see. The format exists already in DRM. >> >>> This patch is meant to move this out of the driver: >>> https://github.com/rhgndf/ms912x/blob/main/ms912x_transfer.c#L153 >>> >>>>> Signed-off-by: Ho Jie Feng >>>>> --- >>>>> This is used for a driver, ms912x that I will be submitting. It only >>>>> supports uyvy framebuffers. >>>> Please resubmit as part of the driver series. We're not going to merge >>>> it without callers anyway. >>>> ... >>>> For naming, please follow the conventions used by the other helpers in >>>> this file. >>> Will send the driver in with this patch and its fixes, thanks for the review. >>> >>>> ... >>>>> + v = drm_pixel_rgb2_to_v_bt601(r, g, b); >>>>> + u = drm_pixel_rgb2_to_u_bt601(r, g, b); >>>>> + >>>>> + transfer_buffer[dst_offset++] = u; >>>>> + transfer_buffer[dst_offset++] = y1; >>>>> + transfer_buffer[dst_offset++] = v; >>>>> + transfer_buffer[dst_offset++] = y2; >>>> Rather that writing bytes individually, use put_unaligned_le32() or a >>>> similar helper. Byte order within a pixel is little endian, although >>>> I'm not sure what this means for UYVY. >>> This is meant to be sent over a usb transfer, so byte order needs to be >>> the same on both little and big endian systems. >> DRM formats always refer to little endian. As it is implemented now, >> it's not clear what the endianess of your output is. Please duplicate >> the other helpers' logic. They all pack the output with appropriate >> helpers. If the USB device requires BE, you have to write a separate >> conversion helper for that. >> >> BTW, you have an OOB access if the line width is not a multiple of 2. > How should I handle this? Rounding it within the helper doesn't seem > to make sense and the function return is a void, so it can't return -EINVAL. It's the callers responsibility to pass in enough pixels. You'll have to take care of it in the driver by rounding the damage area accordingly. It's not optimal but it's not a big deal either. In the line-conversion helper, simply round down to the nearest multiple of 2. > > Other helpers ignore the -ENOMEM error when drm_format_conv_state_reserve > fails, so should it follow this convention? Do you have a specific example? > > Alternatively, drm_fb_xfrm can be exported, and let the driver define > the rgb->yuv coefficients? But I think it is fine since _to_gray8 also > cites BT.601. The current constants seem fine. With the 2-pixel alignment, there shouldn't be any other cases required. Best regards Thomas -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)