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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D606CC19F32 for ; Wed, 5 Mar 2025 18:12:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=u+n5xvxEWFdmJ8BoUg/dUhEOuNDpxyHi20RASTtKrdQ=; b=EiYpdlTVQqnZDSI0BCSgmVX5yB iWO8SFvNV+C1Lvp9PQHrbMc1S54OBhseRVL1U2aLlnqkvSemn3RFwXwSB//y51yBOSQAlVwemPZjZ ugNfKbytbcGrQam6X+hL4SrIlxm0duwWGwRVIsGUxNgtdQxckHntk2ChdFlbKChgqTprXlgRf0tzG //uFX/FpYlgkXIUFL3xEtMOtZQ4mH/oqPeXbnK8+S64ZLuFNNp5YgDj4Qwc575T5RlQr3QxF0JwX4 Bwcn2aMTt0j5R73D3f4XgC9oo+VvsCZCYa7tRoJxC4vxNxqUwiTTjhOQDm1XwplV7G67QtaNpY5lQ aNoPGbcg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tptEc-00000008tMv-1p0w; Wed, 05 Mar 2025 18:12:46 +0000 Received: from bali.collaboradmins.com ([148.251.105.195]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tptAA-00000008sh5-3gGM; Wed, 05 Mar 2025 18:08:12 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1741198089; bh=RSrGA34yP7qtDktQg873/4X5XR2J1ZoUMnU85sv0+14=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BgTVMv1fqV1j9qJ2GNvgOfdOeYCxa7JsX7HymNujv2pzgOhAjxjWwXSRmfJh1ZtSd q8XiB5unEJBko8+PkZ1NJR0TND/dAh8rLegGtjSE481p+QUbIqoc6ZI6FMSc6AwCpz 9d81cYy/gblpx+soZ4ar8a+HBXjnVJSNiGujXU1DAaU6Orddlt/Q+JhZpnMflYQ5mO A2bk7clUtWz38Z0QhdU5v1uG2qKkLVspiGm/8LyNyB6KBpt1TfV3+tDgKKxmhHEmpR vqkF6UnYlgkl06AXSAew8RVcYM0kFfhowcGXAb537SkzF8CtqBD9eMC3q4LWWGsESf GnDhTNmP1RxMw== Received: from [192.168.1.100] (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: kholk11) by bali.collaboradmins.com (Postfix) with ESMTPSA id 2B21117E0599; Wed, 5 Mar 2025 19:08:08 +0100 (CET) Message-ID: Date: Wed, 5 Mar 2025 19:08:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 6/8] soc: mediatek: Add programming flow for unsupported subsys ID hardware To: =?UTF-8?B?SmFzb24tSkggTGluICjmnpfnnb/npaUp?= , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "mchehab@kernel.org" , "chunkuang.hu@kernel.org" , "jassisinghbrar@gmail.com" Cc: "linux-media@vger.kernel.org" , =?UTF-8?B?U2lyaXVzIFdhbmcgKOeOi+eak+aYsSk=?= , =?UTF-8?B?TW91ZHkgSG8gKOS9leWul+WOnyk=?= , =?UTF-8?B?TmFuY3kgTGluICjmnpfmrKPonqIp?= , =?UTF-8?B?WGlhbmRvbmcgV2FuZyAo546L5YWI5YasKQ==?= , "linux-kernel@vger.kernel.org" , Project_Global_Chrome_Upstream_Group , "dri-devel@lists.freedesktop.org" , "linux-mediatek@lists.infradead.org" , "devicetree@vger.kernel.org" , "fshao@chromium.org" , =?UTF-8?B?U2luZ28gQ2hhbmcgKOW8teiIiOWciyk=?= , "linux-arm-kernel@lists.infradead.org" , =?UTF-8?B?WGF2aWVyIENoYW5nICjlvLXnjbvmlocp?= , "matthias.bgg@gmail.com" , "treapking@chromium.org" References: <20250218054405.2017918-1-jason-jh.lin@mediatek.com> <20250218054405.2017918-7-jason-jh.lin@mediatek.com> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250305_100811_066397_667E5857 X-CRM114-Status: GOOD ( 28.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Il 05/03/25 17:12, Jason-JH Lin (林睿祥) ha scritto: > On Tue, 2025-03-04 at 10:41 +0100, AngeloGioacchino Del Regno wrote: >> >> External email : Please do not click links or open attachments until >> you have verified the sender or the content. >> >> >> Il 18/02/25 06:41, Jason-JH Lin ha scritto: >>> To support hardware without subsys IDs on new SoCs, add a >>> programming >>> flow that checks whether the subsys ID is valid. If the subsys ID >>> is >>> invalid, the flow will call 2 alternative CMDQ APIs: >>> cmdq_pkt_assign() and cmdq_pkt_write_s_value() to achieve the same >>> functionality. >>> >>> Signed-off-by: Jason-JH Lin >>> --- >>>   drivers/soc/mediatek/mtk-mmsys.c | 14 +++++++++++--- >>>   drivers/soc/mediatek/mtk-mutex.c | 11 +++++++++-- >>>   2 files changed, 20 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/soc/mediatek/mtk-mmsys.c >>> b/drivers/soc/mediatek/mtk-mmsys.c >>> index bb4639ca0b8c..ce949b863b05 100644 >>> --- a/drivers/soc/mediatek/mtk-mmsys.c >>> +++ b/drivers/soc/mediatek/mtk-mmsys.c >>> @@ -167,9 +167,17 @@ static void mtk_mmsys_update_bits(struct >>> mtk_mmsys *mmsys, u32 offset, u32 mask, >>>       u32 tmp; >>> >>>       if (mmsys->cmdq_base.size && cmdq_pkt) { >>> -             ret = cmdq_pkt_write_mask(cmdq_pkt, mmsys- >>>> cmdq_base.subsys, >>> -                                       mmsys->cmdq_base.offset + >>> offset, val, >>> -                                       mask); >>> +             offset += mmsys->cmdq_base.offset; >>> +             if (mmsys->cmdq_base.subsys != CMDQ_SUBSYS_INVALID) { >> >> You're still anyway passing the subsys to cmdq_pkt_write_mask(), >> right?! >> Why don't you just handle this in cmdq_pkt_write_mask() then? ;-) >> >> I can see this pattern being repeated over and over in both >> drm/mediatek and MDP3 >> drivers, and it's not necessary to duplicate this many times when you >> can write it >> just once. >> >> Would've also been faster for you to implement... :-D >> > > I think did it in the series V1: > https://patchwork.kernel.org/project/linux-mediatek/patch/20241121042602.32730-5-jason-jh.lin@mediatek.com/ > > Because it'll need to passing the base_pa and that will need to change > the interface for original APIs. > > And CK think that's not a necessary to change the APIs. It can be done > by cmdq_pkt_assign() + cmdq_pkt_write_s_mask_value() in the client > drivers. Then you can see this pattern in everywhere. :-) > Using likely(x) and unlikely(x) should be avoided, really, unless it's something that is really really really really ... really ... rea.... likely or unlikely :-) Btw. Changing the APIs is a bit difficult, but I disagree with CK about not "inventing" a new API for the unsupported-subsys flow. It's true, it is not *strictly* needed to add a function, but it's good for any kind of future maintainability - as I explained, it's easier then to fix a problem if there's one.... and well, I can see that you agree with me, because effectively you did it the first time :-) CK mentioned using cmdq_pkt_write() *or* cmdq_pkt_assignwrite/cmdq_pkt_write_pa() (however you wanna call it, it's fine for me), in drivers that know that there always is or there always isn't a subsys ID: that's a good suggestion, as this can be eventually done with assigning a function pointer, so, no conditionals at each operation. My point of view, finally, is: - This is just another way of doing cmdq_pkt_write() - This, at the end of the day, does exactly what cmdq_pkt_write() is doing, except it's doing it with two instructions instead of one; - The same thing can be done in two different ways (depending on SoC) - This same thing should have a function that does it. A function that does it can be int cmdq_pkt_write_pa(struct cmdq_pkt *pkt, u8 subsys /*unused*/, u32 pa_base, u16 offset, u32 value) { err = cmdq_pkt_assign(pkt, 0, CMDQ_ADDR_HIGH(pa_base)); if (err < 0) return err; return cmdq_pkt_write_s_value( .... etc) } int cmdq_pkt_write() <--- unchanged, scheduled for removal after all drivers migrated int cmdq_pkt_write_subsys(struct cmdq_pkt *pkt, u8 subsys, u32 pa_base /*unused*/, u16 offset, u32 value) { /* This function will get the contents of cmdq_pkt_write once removed, but, in the meanwhile, to avoid duplication we just call that: */ return cmdq_pkt_write(pkt, subsys, offset, value); } - Are we adding one more function parameter? Yes - Is this impacting performance overall? Not really After all, we're living in an ARMv8 (actually, ARMv9 for new ones) world, so one more function param won't hurt anyone. I think that's the best of both worlds, and makes everyone happy. Are you happy with that? :-) Cheers, Angelo