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dkim=none Received: from imap2.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap2.dmz-prg2.suse.org (Postfix) with ESMTPS id E5C9A1331E; Wed, 3 Apr 2024 09:32:49 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap2.dmz-prg2.suse.org with ESMTPSA id rI3ONkEiDWbkeQAAn2gu4w (envelope-from ); Wed, 03 Apr 2024 09:32:49 +0000 Message-ID: <15e15564-66f5-4057-8b6f-9361e4b76e76@suse.de> Date: Wed, 3 Apr 2024 11:32:49 +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 v2] drm/ast: Fix soft lockup To: Jammy Huang , jfalempe@redhat.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@redhat.com, airlied@gmail.com, daniel@ffwll.ch Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20240403090246.1495487-1-jammy_huang@aspeedtech.com> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -2.58 X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO X-Spamd-Result: default: False [-2.58 / 50.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; XM_UA_NO_VERSION(0.01)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; TO_DN_SOME(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; MX_GOOD(-0.01)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCPT_COUNT_SEVEN(0.00)[9]; FREEMAIL_TO(0.00)[aspeedtech.com,redhat.com,linux.intel.com,kernel.org,gmail.com,ffwll.ch]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(2.20)[]; MIME_TRACE(0.00)[0:+]; BAYES_HAM(-3.00)[100.00%]; MID_RHS_MATCH_FROM(0.00)[]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; NEURAL_HAM_LONG(-0.98)[-0.981]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DBL_BLOCKED_OPENRESOLVER(0.00)[aspeedtech.com:email,suse.de:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_IN_DNSWL_HI(-0.50)[2a07:de40:b281:104:10:150:64:98:from]; RCVD_TLS_ALL(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:98:from] X-Spam-Level: X-Rspamd-Queue-Id: 3246635194 Am 03.04.24 um 11:02 schrieb Jammy Huang: > There is a while-loop in ast_dp_set_on_off() that could lead to > infinite-loop. This is because the register, VGACRI-Dx, checked in > this API is a scratch register actually controlled by a MCU, named > DPMCU, in BMC. > > These scratch registers are protected by scu-lock. If suc-lock is not > off, DPMCU can not update these registers and then host will have soft > lockup due to never updated status. > > DPMCU is used to control DP and relative registers to handshake with > host's VGA driver. Even the most time-consuming task, DP's link > training, is less than 100ms. 200ms should be enough. > > Signed-off-by: Jammy Huang > Reviewed-by: Jocelyn Falempe Reviewed-by: Thomas Zimmermann > --- > drivers/gpu/drm/ast/ast_dp.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c > index ebb6d8ebd44e..1e9259416980 100644 > --- a/drivers/gpu/drm/ast/ast_dp.c > +++ b/drivers/gpu/drm/ast/ast_dp.c > @@ -180,6 +180,7 @@ void ast_dp_set_on_off(struct drm_device *dev, bool on) > { > struct ast_device *ast = to_ast_device(dev); > u8 video_on_off = on; > + u32 i = 0; > > // Video On/Off > ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xE3, (u8) ~AST_DP_VIDEO_ENABLE, on); > @@ -192,6 +193,8 @@ void ast_dp_set_on_off(struct drm_device *dev, bool on) > ASTDP_MIRROR_VIDEO_ENABLE) != video_on_off) { > // wait 1 ms > mdelay(1); > + if (++i > 200) > + break; > } > } > } > > base-commit: b0546776ad3f332e215cebc0b063ba4351971cca -- -- 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)