From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH v2] i2c: nvidia-gpu: Handle timeout correctly in gpu_i2c_check_status() Date: Tue, 24 Mar 2020 15:41:24 +0200 Message-ID: <20200324134124.GL1922688@smile.fi.intel.com> References: <20200324130712.12289-1-kai.heng.feng@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mga04.intel.com ([192.55.52.120]:8751 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726802AbgCXNlY (ORCPT ); Tue, 24 Mar 2020 09:41:24 -0400 Content-Disposition: inline In-Reply-To: <20200324130712.12289-1-kai.heng.feng@canonical.com> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Kai-Heng Feng Cc: ajayg@nvidia.com, Wolfram Sang , "open list:I2C CONTROLLER DRIVER FOR NVIDIA GPU" , open list On Tue, Mar 24, 2020 at 09:07:12PM +0800, Kai-Heng Feng wrote: > Nvidia card may come with a "phantom" UCSI device, and its driver gets > stuck in probe routine, prevents any system PM operations like suspend. > > When the target time equals to jiffies, it's not included by > time_is_before_jiffies(). So let's use a boolean to make sure the > operation is done or timeout. Thank you for an update, my comments below. > unsigned long target = jiffies + msecs_to_jiffies(1000); > u32 val; > + bool done = false; > > do { > val = readl(i2cd->regs + I2C_MST_CNTL); > - if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER)) > - break; > - if ((val & I2C_MST_CNTL_STATUS) != > - I2C_MST_CNTL_STATUS_BUS_BUSY) > + if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER) > + || (val & I2C_MST_CNTL_STATUS) != > + I2C_MST_CNTL_STATUS_BUS_BUSY) { Bad formatting. But see below. > + done = true; > break; > + } > usleep_range(500, 600); > } while (time_is_after_jiffies(target)); > > - if (time_is_before_jiffies(target)) { > + if (!done) { > dev_err(i2cd->dev, "i2c timeout error %x\n", val); > return -ETIMEDOUT; > } Overall it can use simple tries since you already have sleep inside, but moreover, you may simple switch to readl_poll_timeout() this entire loop. -- With Best Regards, Andy Shevchenko