From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 802EBEE6B6C for ; Sat, 7 Feb 2026 00:23:09 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3976810E1BB; Sat, 7 Feb 2026 00:23:09 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="CqIiizZU"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8AC7E10E1BB for ; Sat, 7 Feb 2026 00:23:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1770423788; x=1801959788; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=vZMScRabhY9YT5Y2rcY3aUG21/5D1gyemH5lFEEvPVo=; b=CqIiizZUo3YzUb8XjtcZdS/R1+Ct6A8m0L7BvUBHMAJU8o5HvnzpV8jw 1Pp//IeIMsm//MBSr7ZjYHZ9toaPtXAWV57BNsSVHS4wSN0UuOwA4LmJf HH2OuvSaKOw4qE2a8PJwtBT4JDwS4KH1Q4IDH5OnJ9cbtgVRHTyJqVtXT 0OYMxBGVNgwvwLFjeVo9h84PHc0Tzb7rskYRV79QM35ShygfP5UbQqyaF QbQuJs2GMU1rsvkZ+lOAgb+2rqYsa6XHwTJlWZZH8MFzCb9e8kWzt/0pE GEcVWHT83PD0lbS1CsUNuxkjIXQwdF2iG7KZOk0YE/DMI9Lt5xbf7PGb+ w==; X-CSE-ConnectionGUID: tnLuG0i9QO62kWxQRVEAMw== X-CSE-MsgGUID: qBMZlo6GRQqWeF/PyRzlhw== X-IronPort-AV: E=McAfee;i="6800,10657,11693"; a="70649427" X-IronPort-AV: E=Sophos;i="6.21,277,1763452800"; d="scan'208";a="70649427" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2026 16:23:07 -0800 X-CSE-ConnectionGUID: cbP8GYQLR0edSDhMdKK59g== X-CSE-MsgGUID: mdtOqoBpTMqCMuO6lRKWyw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,277,1763452800"; d="scan'208";a="215530593" Received: from mdroper-desk1.fm.intel.com ([10.1.39.133]) by orviesa004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Feb 2026 16:23:06 -0800 From: Matt Roper To: intel-xe@lists.freedesktop.org Cc: matthew.d.roper@intel.com Subject: [PATCH] drm/xe/reg_sr: Add debugfs to verify status of reg_sr programming Date: Fri, 6 Feb 2026 16:23:05 -0800 Message-ID: <20260207002304.585103-2-matthew.d.roper@intel.com> X-Mailer: git-send-email 2.52.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" When applying save-restore register programming for workarounds, tuning settings, and general device configuration we assume the programming was successful. However there are a number of cases where the desired reg_sr programming can become lost: - workarounds implemented on the wrong RTP table might not get saved/restored at the right time leading to, for example, failure to re-apply the programming after engine resets - some hardware registers become "locked" and can no longer be updated after firmware or the driver finishes initializing them - sometimes the hardware teams just made a mistake when documenting the register and/or bits that needed to be programmed Add a debugfs entry that will read back the registers referenced on a GT's save-restore lists and print any cases where the desired programming is no longer in effect. Such cases might indicate the presence of a driver/firmware bug, might indicate that the documentation we were following has a mistake, or might be benign (occasionally registers have broken read-back capability preventing verification, but previous writes were still successful and effective). For now we only verify the GT and engine reg_sr lists. Verifying the LRC list will require checking the expected programming against the default_lrc contents, not the live registers (which may not reflect the reg_sr programming if no context is actively running). Signed-off-by: Matt Roper --- drivers/gpu/drm/xe/xe_gt_debugfs.c | 26 +++++++++++++++++++++++ drivers/gpu/drm/xe/xe_reg_sr.c | 34 ++++++++++++++++++++++++++++++ drivers/gpu/drm/xe/xe_reg_sr.h | 3 +++ 3 files changed, 63 insertions(+) diff --git a/drivers/gpu/drm/xe/xe_gt_debugfs.c b/drivers/gpu/drm/xe/xe_gt_debugfs.c index 4363bc9c3606..aa43427a9f4b 100644 --- a/drivers/gpu/drm/xe/xe_gt_debugfs.c +++ b/drivers/gpu/drm/xe/xe_gt_debugfs.c @@ -155,6 +155,30 @@ static int register_save_restore(struct xe_gt *gt, struct drm_printer *p) return 0; } +/* + * Check the registers referenced on a save-restore list and report any + * save-restore entries that did not get applied. + */ +static int register_save_restore_check(struct xe_gt *gt, struct drm_printer *p) +{ + struct xe_hw_engine *hwe; + enum xe_hw_engine_id id; + + CLASS(xe_force_wake, fw_ref)(gt_to_fw(gt), XE_FORCEWAKE_ALL); + if (!xe_force_wake_ref_has_domain(fw_ref.domains, XE_FORCEWAKE_ALL)) { + drm_printf(p, "ERROR: Could not acquire forcewake\n"); + return -ETIMEDOUT; + } + + xe_reg_sr_readback_check(>->reg_sr, gt, p); + for_each_hw_engine(hwe, gt, id) + xe_reg_sr_readback_check(&hwe->reg_sr, gt, p); + + /* TODO: Check hwe->reg_lrc against contents of default_lrc. */ + + return 0; +} + static int rcs_default_lrc(struct xe_gt *gt, struct drm_printer *p) { xe_lrc_dump_default(p, gt, XE_ENGINE_CLASS_RENDER); @@ -209,6 +233,8 @@ static const struct drm_info_list vf_safe_debugfs_list[] = { { "default_lrc_vecs", .show = xe_gt_debugfs_show_with_rpm, .data = vecs_default_lrc }, { "hwconfig", .show = xe_gt_debugfs_show_with_rpm, .data = hwconfig }, { "pat_sw_config", .show = xe_gt_debugfs_simple_show, .data = xe_pat_dump_sw_config }, + { "register-save-restore-check", + .show = xe_gt_debugfs_show_with_rpm, .data = register_save_restore_check }, }; /* everything else should be added here */ diff --git a/drivers/gpu/drm/xe/xe_reg_sr.c b/drivers/gpu/drm/xe/xe_reg_sr.c index d3e13ea33123..37555d5211d8 100644 --- a/drivers/gpu/drm/xe/xe_reg_sr.c +++ b/drivers/gpu/drm/xe/xe_reg_sr.c @@ -204,3 +204,37 @@ void xe_reg_sr_dump(struct xe_reg_sr *sr, struct drm_printer *p) str_yes_no(entry->reg.masked), str_yes_no(entry->reg.mcr)); } + +static u32 readback_reg(struct xe_gt *gt, struct xe_reg reg) +{ + struct xe_reg_mcr mcr_reg = to_xe_reg_mcr(reg); + + if (reg.mcr) + return xe_gt_mcr_unicast_read_any(gt, mcr_reg); + else + return xe_mmio_read32(>->mmio, reg); +} + +/** + * xe_reg_sr_readback_check() - Readback registers referenced in save/restore + * entries and check whether the programming is in place. + * @sr: Save/restore entries + * @gt: GT to read register from + * @p: DRM printer to report discrepancies on + */ +void xe_reg_sr_readback_check(struct xe_reg_sr *sr, + struct xe_gt *gt, + struct drm_printer *p) +{ + struct xe_reg_sr_entry *entry; + unsigned long offset; + + xa_for_each(&sr->xa, offset, entry) { + u32 val = readback_reg(gt, entry->reg); + u32 mask = entry->clr_bits | entry->set_bits; + + if ((val & mask) != entry->set_bits) + drm_printf(p, "%#8lx & %#10x :: expected %#10x got %#10x\n", + offset, mask, entry->set_bits, val & mask); + } +} diff --git a/drivers/gpu/drm/xe/xe_reg_sr.h b/drivers/gpu/drm/xe/xe_reg_sr.h index 51fbba423e27..cd133a09aa9b 100644 --- a/drivers/gpu/drm/xe/xe_reg_sr.h +++ b/drivers/gpu/drm/xe/xe_reg_sr.h @@ -19,6 +19,9 @@ struct drm_printer; int xe_reg_sr_init(struct xe_reg_sr *sr, const char *name, struct xe_device *xe); void xe_reg_sr_dump(struct xe_reg_sr *sr, struct drm_printer *p); +void xe_reg_sr_readback_check(struct xe_reg_sr *sr, + struct xe_gt *gt, + struct drm_printer *p); int xe_reg_sr_add(struct xe_reg_sr *sr, const struct xe_reg_sr_entry *e, struct xe_gt *gt); -- 2.52.0