From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B7B43128BE; Mon, 5 Jan 2026 09:12:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767604354; cv=none; b=jIHQECzTz8VlOYq5PjAizFoa3bauhAkr7dILWuggVGnqn4Rr2RmglspyfMBbfLwBODCWM8nX1ghGGc7Y53Pv0llYD5fPNLUK9ZjMGqmpuF3eSTF5tT2kiwdSOa9xtp56zGdphCRejUepZG0YCNglog7u8hwG9RjKA996t5dVvkg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767604354; c=relaxed/simple; bh=C1W9fhxW+cUNMF7uiOONv8Z5SsvysSW3gf1k1fchxsA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=K12BYasCVPweCEpW8F5VG9j8gxigi7yz2u5pMTpi5hwBah8uzv7xkSc91HWC6ThU0HCOZBcpUx+Qzjrf3PlOzj2Z+6oTlZ7EIQYeOgbegGFAsvrsTpRnf5hOwkCTCS9m3iCI+MNVwiJMhsmZo5sfuxHW0zR+uUx9cIiGyxkkx1Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0QrqJXdy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0QrqJXdy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 255DAC116D0; Mon, 5 Jan 2026 09:12:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767604353; bh=C1W9fhxW+cUNMF7uiOONv8Z5SsvysSW3gf1k1fchxsA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=0QrqJXdyG9H25q8C1UEzy0ortPamAS8mDa++XynbWKs98Z7kY4MX9CegkgDuec7YD 5rH4QGvO3ppox96pZOcF1gznK2iQ4S+xjDb4S9Vy+oFTnX8y7vjUXKSj4k24hfPmuL uXBqik97J/q77Hiw2mVqQBC1IbgxgyVerqDqRmIA= Date: Mon, 5 Jan 2026 10:12:30 +0100 From: Greg KH To: sun jian Cc: linux-staging@lists.linux.dev, sudipm.mukherjee@gmail.com, teddy.wang@siliconmotion.com, linux-fbdev@vger.kernel.org Subject: Re: [PATCH v2] staging: sm750fb: fix unused tmp in sw_i2c_wait Message-ID: <2026010555-surely-uncheck-bac2@gregkh> References: <20260105021026.556244-1-sun.jian.kdev@gmail.com> <20260105074917.607201-1-sun.jian.kdev@gmail.com> <2026010505-surging-resurface-a7d3@gregkh> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Jan 05, 2026 at 04:57:48PM +0800, sun jian wrote: > Hi Greg, > > Sorry about that — I mistakenly replied only to you. > > As you pointed out, sw_i2c_wait() sits on the bit-banged I2C GPIO > transitions, so changing the delay semantics without hardware validation > is risky. I don't have access to the hardware to validate timing/behavior, > and I can't justify that udelay(1) is equivalent to the existing loop. > > Please ignore v2 (and v1). I won't resend a warning-only workaround. > > If someone with the hardware can help validate a proper fix (e.g. a > well-justified time-based delay, or reworking this to use a proper I2C > bit-banging helper), I'm happy to revisit. A time-based one is going to be the correct solution as every cpu will run that "let's count some numbers" loop at a different speed :( thanks, greg k-h