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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: EE2B91FB99 X-Spam-Score: -6.50 X-Spam-Level: X-Spam-Flag: NO X-Spamd-Result: default: False [-6.50 / 50.00]; BAYES_HAM(-3.00)[100.00%]; DWL_DNSWL_MED(-2.00)[suse.de:dkim]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-0.998]; MIME_GOOD(-0.10)[text/plain]; XM_UA_NO_VERSION(0.01)[]; MX_GOOD(-0.01)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_DN_SOME(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_DN_EQ_ADDR_SOME(0.00)[]; FREEMAIL_TO(0.00)[nxp.com,oss.nxp.com,linux.intel.com,kernel.org,gmail.com,redhat.com,lists.freedesktop.org,vger.kernel.org]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:dkim]; RCPT_COUNT_SEVEN(0.00)[8]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from] X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org Hi Am 12.06.24 um 10:45 schrieb Daniel Vetter: > On Tue, Jun 11, 2024 at 11:29:58AM +0200, Thomas Zimmermann wrote: >> Hi >> >> Am 11.06.24 um 10:23 schrieb Peng Fan: >>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start >>>> >>>> Hi >>>> >>>> Am 11.06.24 um 03:00 schrieb Peng Fan: >>>>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start >>>>>> >>>>>> Hi >>>>>> >>>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>>>>>> From: Peng Fan >>>>>>> >>>>>>> If 'info->screen_buffer' locates in vmalloc address space, >>>>>>> virt_to_page will not be able to get correct results. With >>>>>>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64, >>>>>> there is dump below: >>>>>> >>>>>> Which graphics driver triggers this bug? >>>>> It is NXP i.MX95 DPU driver which is still in NXP downstream repo. >>>> Which DRM memory manager does that driver use? >>> DRM_GEM_DMA_DRIVER_OPS >> So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't you >> allocate from one of these dma_alloc_() calls at [1] ? How does the drivers >> end up with vmalloc'd fbdev memory? Specifically in the light of the docs at >> [2]. > I think when you have an iommu dma_alloc just allocates pages, and uses > the iommu to make it all contiguous for the device, and vmalloc for the > kernel. So it's not allocated with vmalloc(), just ends up getting mapped > into the vmalloc range. Thanks, that makes sense. As I mentioned in another reply, it might make sense to protect smem_start with an opt-in flag for only that single driver that needs it. Best regards Thomas > -Sima > > >> [1] https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146 >> [2] https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124 >> >> Best regards >> Thomas >> >>>> I'm asking because if the driver allocates BOs via vmalloc(), should it really >>>> use fbdev-dma? >>> We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0, >>> fbdev emulation could be disabled. >>> >>> Thanks >>> Peng >>>> Best regards >>>> Thomas >>>> >>>>> Thanks, >>>>> Peng. >>>> -- >>>> -- >>>> 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) >> -- >> -- >> 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) >> -- -- 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)