From patchwork Tue May 7 03:11:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aaron Ma X-Patchwork-Id: 1932205 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com (client-ip=185.125.189.65; helo=lists.ubuntu.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=patchwork.ozlabs.org) Received: from lists.ubuntu.com (lists.ubuntu.com [185.125.189.65]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4VYNcZ6xcvz20fX for ; Tue, 7 May 2024 13:12:30 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=lists.ubuntu.com) by lists.ubuntu.com with esmtp (Exim 4.86_2) (envelope-from ) id 1s4BFT-0003vL-2f; Tue, 07 May 2024 03:12:11 +0000 Received: from smtp-relay-canonical-0.internal ([10.131.114.83] helo=smtp-relay-canonical-0.canonical.com) by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1s4BFQ-0003up-A9 for kernel-team@lists.ubuntu.com; Tue, 07 May 2024 03:12:08 +0000 Received: from localhost.localdomain (unknown [222.129.33.118]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-0.canonical.com (Postfix) with ESMTPSA id CE0433F1B7 for ; Tue, 7 May 2024 03:12:06 +0000 (UTC) From: Aaron Ma To: kernel-team@lists.ubuntu.com Subject: [N][PATCH 1/1] HID: i2c-hid: Revert to await reset ACK before reading report descriptor Date: Tue, 7 May 2024 11:11:56 +0800 Message-ID: <20240507031156.8333-2-aaron.ma@canonical.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240507031156.8333-1-aaron.ma@canonical.com> References: <20240507031156.8333-1-aaron.ma@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Kenny Levinsen BugLink: https://bugs.launchpad.net/bugs/2061040 In af93a167eda9, i2c_hid_parse was changed to continue with reading the report descriptor before waiting for reset to be acknowledged. This has lead to two regressions: 1. We fail to handle reset acknowledgment if it happens while reading the report descriptor. The transfer sets I2C_HID_READ_PENDING, which causes the IRQ handler to return without doing anything. This affects both a Wacom touchscreen and a Sensel touchpad. 2. On a Sensel touchpad, reading the report descriptor this quickly after reset results in all zeroes or partial zeroes. The issues were observed on the Lenovo Thinkpad Z16 Gen 2. The change in question was made based on a Microsoft article[0] stating that Windows 8 *may* read the report descriptor in parallel with awaiting reset acknowledgment, intended as a slight reset performance optimization. Perhaps they only do this if reset is not completing quickly enough for their tastes? As the code is not currently ready to read registers in parallel with a pending reset acknowledgment, and as reading quickly breaks the report descriptor on the Sensel touchpad, revert to waiting for reset acknowledgment before proceeding to read the report descriptor. [0]: https://learn.microsoft.com/en-us/windows-hardware/drivers/hid/plug-and-play-support-and-power-management Fixes: af93a167eda9 ("HID: i2c-hid: Move i2c_hid_finish_hwreset() to after reading the report-descriptor") Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2271136 Cc: stable@vger.kernel.org Signed-off-by: Kenny Levinsen Link: https://lore.kernel.org/r/20240331182440.14477-1-kl@kl.wtf [hdegoede@redhat.com Drop no longer necessary abort_reset error exit path] Signed-off-by: Hans de Goede Tested-by: Mark Pearson Signed-off-by: Jiri Kosina (cherry picked from commit ea36bf1827462e4a52365bf8e3f7d1712c5d9600) Signed-off-by: Aaron Ma --- drivers/hid/i2c-hid/i2c-hid-core.c | 29 ++++++++--------------------- 1 file changed, 8 insertions(+), 21 deletions(-) diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c index 2df1ab3c31cc..13d67d7c67b4 100644 --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -735,12 +735,15 @@ static int i2c_hid_parse(struct hid_device *hid) mutex_lock(&ihid->reset_lock); do { ret = i2c_hid_start_hwreset(ihid); - if (ret) + if (ret == 0) + ret = i2c_hid_finish_hwreset(ihid); + else msleep(1000); } while (tries-- > 0 && ret); + mutex_unlock(&ihid->reset_lock); if (ret) - goto abort_reset; + return ret; use_override = i2c_hid_get_dmi_hid_report_desc_override(client->name, &rsize); @@ -750,11 +753,8 @@ static int i2c_hid_parse(struct hid_device *hid) i2c_hid_dbg(ihid, "Using a HID report descriptor override\n"); } else { rdesc = kzalloc(rsize, GFP_KERNEL); - - if (!rdesc) { - ret = -ENOMEM; - goto abort_reset; - } + if (!rdesc) + return -ENOMEM; i2c_hid_dbg(ihid, "asking HID report descriptor\n"); @@ -763,23 +763,10 @@ static int i2c_hid_parse(struct hid_device *hid) rdesc, rsize); if (ret) { hid_err(hid, "reading report descriptor failed\n"); - goto abort_reset; + goto out; } } - /* - * Windows directly reads the report-descriptor after sending reset - * and then waits for resets completion afterwards. Some touchpads - * actually wait for the report-descriptor to be read before signalling - * reset completion. - */ - ret = i2c_hid_finish_hwreset(ihid); -abort_reset: - clear_bit(I2C_HID_RESET_PENDING, &ihid->flags); - mutex_unlock(&ihid->reset_lock); - if (ret) - goto out; - i2c_hid_dbg(ihid, "Report Descriptor: %*ph\n", rsize, rdesc); ret = hid_parse_report(hid, rdesc, rsize);