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[109.252.139.36]) by smtp.googlemail.com with ESMTPSA id z13sm141770lfr.183.2022.01.19.04.20.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Jan 2022 04:20:36 -0800 (PST) Message-ID: Date: Wed, 19 Jan 2022 15:20:35 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH 1/6] i2c: tegra: Add support for Tegra234 I2C Content-Language: en-US To: Akhil R , "robh+dt@kernel.org" , "thierry.reding@gmail.com" , Jonathan Hunter , Mikko Perttunen , Laxman Dewangan , "linux-i2c@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Petlozu Pravareshwar References: <1642080623-15980-1-git-send-email-akhilrajeev@nvidia.com> <1642080623-15980-2-git-send-email-akhilrajeev@nvidia.com> From: Dmitry Osipenko In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 19.01.2022 11:20, Akhil R пишет: >> 13.01.2022 16:30, Akhil R пишет: >>> +static const struct tegra_i2c_hw_feature tegra234_i2c_hw = { >>> + .has_continue_xfer_support = true, >>> + .has_per_pkt_xfer_complete_irq = true, >>> + .clk_divisor_hs_mode = 0x2, >>> + .clk_divisor_std_mode = 0x4f, >>> + .clk_divisor_fast_mode = 0x58, >>> + .clk_divisor_fast_plus_mode = 0x24, >>> + .has_config_load_reg = true, >>> + .has_multi_master_mode = true, >>> + .has_slcg_override_reg = true, >>> + .has_mst_fifo = true, >>> + .quirks = &tegra194_i2c_quirks, >>> + .supports_bus_clear = true, >>> + .has_apb_dma = false, >>> + .tlow_std_mode = 0x8, >>> + .thigh_std_mode = 0x7, >>> + .tlow_fast_fastplus_mode = 0x1, >>> + .thigh_fast_fastplus_mode = 0x1, >>> + .setup_hold_time_std_mode = 0x08080808, >>> + .setup_hold_time_fast_fast_plus_mode = 0x02020202, >>> + .setup_hold_time_hs_mode = 0x090909, >>> + .has_interface_timing_reg = true, }; >> >> Why tegra194_i2c_hw can't be reused by T234? Looks like I2C h/w hasn't >> changed and somebody just made a minor tuning of the timing parameters, does >> it really matter in practice? > The timing parameters are important to get the desired data rate for I2C. The values, > unfortunately, cannot be reused from Tegra194. >From where those T194 parameters specified in the Tegra I2C driver came from? I'm now looking at T194 TRM (Xavier_TRM_DP09253002_v1.3p 10.2.3.1.1 Example Settings for Various I2C Speeds) and see that all the values should match T234. Please check whether T194 configuration is correct and fix it if needed.