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 lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (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 AA083C9833F for ; Mon, 28 Sep 2026 14:01:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xBBui-0004h7-TO; Mon, 28 Sep 2026 10:01:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xBBuY-0004cl-3R for qemu-devel@nongnu.org; Mon, 28 Sep 2026 10:00:56 -0400 Received: from mail-wm2-x10.google.com ([2a00:1450:4864:31::10]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1xBBuU-00038p-B0 for qemu-devel@nongnu.org; Mon, 28 Sep 2026 10:00:53 -0400 Received: by mail-wm2-x10.google.com with SMTP id 5b1f17b1804b1-49ffa15f67fso10830915e9.2 for ; Mon, 28 Sep 2026 07:00:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1790604048; x=1791208848; darn=nongnu.org; h=content-transfer-encoding:content-type:mime-version:message-id:date :user-agent:references:in-reply-to:subject:cc:to:from:from:to:cc :subject:date:message-id:reply-to:content-type; bh=LBbN8Oo6oa6n+1aLPrPR5Awrkq9UXBigcfmWzrk2yEA=; b=LUEonE3FUbE7rB24bgub9x38XJYIrAwZx/8vBan1NwVsdMFyiQOq8w59IP7uFzouEr BGp8VGTggWlGOPJCROPPu7Kj6Hu6Qq+lgO+UQWs0Xt+0a8GdaVADEck8QbCNsoylqgfc Uuzsbw8LFfxg6DlwgPcVTvWVjdGaN96h0XRlvwg+hzMBmDwNgGaAd7UtsQZtyWH+c8gw A3gK5xY+NvKwAWUIvgHMpdBWCpDRBXoF0IZSgywVSQn1fsIOo4biciC9yXCigr7Z/mKa 3M7xY8VqaNDkiC/Bs9bYtLTNGAwpt8x3HSJ0SnD3pGKGid9u7kMynghj1SYRmUgea2CM dSZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790604048; x=1791208848; h=content-transfer-encoding:content-type:mime-version:message-id:date :user-agent:references:in-reply-to:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=LBbN8Oo6oa6n+1aLPrPR5Awrkq9UXBigcfmWzrk2yEA=; b=qfWrcf02cSE6YnOBNv9wypPSgm/s4Xl6YcoFi6TGZO5hPhKEP2H/+0ymhdNF8dm2nn 0F5goSeXuRBX1hif+IgKfHJBBYYnwkwAZqm2R4sW+SL/Y77RKuwNkKvFcVS69bFDMTvq fYW++YWNok96kiVMm8V3YiIdORTUjxxcYTXdLDcO/Dyjrp8yE4hBCrbgAeq71dJiN2S7 t4DZyFD4Pl87ukbmvp+ixYOwfm7QaHUK2OTL/iDDUDm3gCJiXTFBfcgTCvpNdMV2LKsC H5VV8ElUG7v98aqKAKK2L5nzgPlQW8EsAa49gcwiKLiFaJSewfglB1TSaiV/AiC1a7pB JYCg== X-Gm-Message-State: AFuF++koLu1ePtIaXm6KkCJSyJD4o0TzACKcsKTzEf7fixsrGM00aR8O ZZDf8sqzk9WY5ElmLx8dKqgXOxsXRLTZKCLKQ6/0tBjrDzG+rKnSjfgrLFxMOxeS5Uw= X-Gm-Gg: AYBFou2CjL4tZbzn+fmV7aOmlCeKj6G7iCl3q3bXI628O1NgiErcaJQK74rrbmmrjG6 UBfCuzHv82qyYS2dMsz9A3VKa+llrXVQRHXqjeMLcdm4s9/R5h2gJOA9Z3r70cWsDAD0NtG2i24 N72sN8338zjQ7biBss0A8HjNBndsKLHzQS89MgHY7Hfoja34nCO9yf2fncyAZTHUGYZcAMpgA/b TkxVMQVg5NgbUkaUy+rg1gJ5ldiZyT7rSB3WI3nv21fjZb5/4mUd9Y8lDQNQj1ECviM9uNq077H 4A9eaGrLnFbEIvbq4GbL/VNDFRoxweSWlogrfh3ZvMIyWDVUKwbuYdYk0puyMouUESVAE/CNXci eDslBeAFO1WL3AfOMmdiHGgjR6Wns33EkLEniWduMbwGRFKUryQdKSHGx9ulb10+JTl2hvv8DUj fqqS6SU2f9MvbRlIuSZptELSAjon8UzJqkd+60BLKw9F8oLGrUBV5/e5Si8L8fBEwLZ6KjxQ== X-Received: by 2002:a05:600c:1c25:b0:49f:ce78:3561 with SMTP id 5b1f17b1804b1-49fe66f19demr255506385e9.18.1790604048219; Mon, 28 Sep 2026 07:00:48 -0700 (PDT) Received: from draig.lan ([185.124.0.156]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a007fd182csm44625565e9.2.2026.09.28.07.00.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 07:00:46 -0700 (PDT) Received: from draig (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id AF1125F8C1; Mon, 28 Sep 2026 15:00:45 +0100 (BST) From: =?utf-8?Q?Alex_Benn=C3=A9e?= To: Soumyajyotii Ssarkar Cc: qemu-devel@nongnu.org, Richard Henderson , Paolo Bonzini , Soumyajyotii Ssarkar , Michael Tokarev , Thomas Lambertz , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Alex Golovko , ShengYi Hung Subject: Re: [RFC PATCH 5/5] input/hid: apply multiplier scaling with residual accumulation In-Reply-To: <20260331170823.72511-6-soumyajyotisarkar23@gmail.com> (Soumyajyotii Ssarkar's message of "Tue, 31 Mar 2026 22:38:23 +0530") References: <20260331170823.72511-1-soumyajyotisarkar23@gmail.com> <20260331170823.72511-6-soumyajyotisarkar23@gmail.com> User-Agent: mu4e 1.14.4-pre4; emacs 30.1 Date: Mon, 28 Sep 2026 15:00:45 +0100 Message-ID: <87se2ta31u.fsf@draig.linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:31::10; envelope-from=alex.bennee@linaro.org; helo=mail-wm2-x10.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Soumyajyotii Ssarkar writes: > Implement multiplier-based scaling with residual accumulation for > fine-grained mouse wheel and pan sensitivity control in report mode. > > Applies divisor based scaling (1, 4, 8, 16) based on negotiated > multiplier values. > Then uses residual based approach to prevent precision loss: > > residual +=3D delta > output =3D residual / divisor > residual -=3D output * divisor > > Residual state preserved across VM migrations via VMState. > > Signed-off-by: Soumyajyotii Ssarkar > --- > hw/input/hid.c | 60 ++++++++++++++++++++++++++++++++++++++++++ > include/hw/input/hid.h | 2 ++ > 2 files changed, 62 insertions(+) > > diff --git a/hw/input/hid.c b/hw/input/hid.c > index d0b7af7c13..9b800faeb0 100644 > --- a/hw/input/hid.c > +++ b/hw/input/hid.c > @@ -365,6 +365,7 @@ void hid_pointer_activate(HIDState *hs) > int hid_pointer_poll(HIDState *hs, uint8_t *buf, int len) > { > int dx, dy, dz, pan, l; > + int wheel_divisor, pan_divisor; > int index; > HIDPointerEvent *e; > > @@ -392,6 +393,54 @@ int hid_pointer_poll(HIDState *hs, uint8_t *buf, int= len) > e->pan -=3D pan; > > > + if (hs->kind =3D=3D HID_MOUSE && hs->protocol !=3D 0) { > + switch (hs->ptr.wheel_multiplier & 0x03) { > + case 0: > + wheel_divisor =3D 1; > + break; > + case 1: > + wheel_divisor =3D 4; > + break; > + case 2: > + wheel_divisor =3D 8; > + break; > + default: > + wheel_divisor =3D 16; > + break; > + } > + > + switch (hs->ptr.pan_multiplier & 0x03) { > + case 0: > + pan_divisor =3D 1; > + break; > + case 1: > + pan_divisor =3D 4; > + break; > + case 2: > + pan_divisor =3D 8; > + break; > + default: > + pan_divisor =3D 16; > + break; > + } > + > + if (wheel_divisor > 1) { > + hs->ptr.wheel_residual +=3D dz; > + dz =3D hs->ptr.wheel_residual / wheel_divisor; > + hs->ptr.wheel_residual -=3D dz * wheel_divisor; > + } else { > + hs->ptr.wheel_residual =3D 0; > + } > + > + if (pan_divisor > 1) { > + hs->ptr.pan_residual +=3D pan; > + pan =3D hs->ptr.pan_residual / pan_divisor; > + hs->ptr.pan_residual -=3D pan * pan_divisor; > + } else { > + hs->ptr.pan_residual =3D 0; > + } > + } > + > if (hs->n && > !e->dz && > !e->pan && > @@ -405,6 +454,7 @@ int hid_pointer_poll(HIDState *hs, uint8_t *buf, int = len) > dz =3D 0 - dz; > pan =3D 0 - pan; > l =3D 0; > + > switch (hs->kind) { > case HID_MOUSE: > if (hs->protocol =3D=3D 0) { > @@ -528,6 +578,11 @@ void hid_reset(HIDState *hs) > case HID_MOUSE: > case HID_TABLET: > memset(hs->ptr.queue, 0, sizeof(hs->ptr.queue)); > + hs->ptr.mouse_grabbed =3D 0; > + hs->ptr.wheel_multiplier =3D 0; > + hs->ptr.pan_multiplier =3D 0; > + hs->ptr.wheel_residual =3D 0; > + hs->ptr.pan_residual =3D 0; > break; > } > hs->head =3D 0; > @@ -619,6 +674,7 @@ static const VMStateDescription vmstate_hid_ptr_queue= =3D { > VMSTATE_INT32(xdx, HIDPointerEvent), > VMSTATE_INT32(ydy, HIDPointerEvent), > VMSTATE_INT32(dz, HIDPointerEvent), > + VMSTATE_INT32(pan, HIDPointerEvent), > VMSTATE_INT32(buttons_state, HIDPointerEvent), > VMSTATE_END_OF_LIST() > } > @@ -636,6 +692,10 @@ const VMStateDescription vmstate_hid_ptr_device =3D { > VMSTATE_UINT32(n, HIDState), > VMSTATE_INT32(protocol, HIDState), > VMSTATE_UINT8(idle, HIDState), > + VMSTATE_UINT8(ptr.wheel_multiplier, HIDState), > + VMSTATE_UINT8(ptr.pan_multiplier, HIDState), > + VMSTATE_INT32(ptr.wheel_residual, HIDState), > + VMSTATE_INT32(ptr.pan_residual, HIDState), > VMSTATE_END_OF_LIST(), If you update migration state you also need to ensure that older systems can be migrated to newer ones. There are some docs in docs/devel that give some guidance on handling these cases.=20 > } > }; > diff --git a/include/hw/input/hid.h b/include/hw/input/hid.h > index 1a1941d371..db902fa023 100644 > --- a/include/hw/input/hid.h > +++ b/include/hw/input/hid.h > @@ -25,6 +25,8 @@ typedef struct HIDMouseState { > int mouse_grabbed; > uint8_t wheel_multiplier; > uint8_t pan_multiplier; > + int32_t wheel_residual; > + int32_t pan_residual; > } HIDMouseState; > > typedef struct HIDKeyboardState { --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro