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Mon, 15 Jul 2019 08:38:57 +0000 (GMT) Subject: Re: [PATCH 1/2] regmap: Add DSI bus support To: Mark Brown Cc: Jeffrey Hugo , Laurent.pinchart@ideasonboard.com, airlied@linux.ie, daniel@ffwll.ch, robdclark@gmail.com, bjorn.andersson@linaro.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org From: Andrzej Hajda Message-ID: <8b74afa7-65ed-c53d-3dc2-d758361f2d62@samsung.com> Date: Mon, 15 Jul 2019 10:38:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.0 MIME-Version: 1.0 In-Reply-To: <20190711145045.GI14859@sirena.co.uk> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA02Sa0hTcRjG/e9cdhxNjtPwxSLzdKPsYtHlhEs0Ik4fkqgQKsRmHjTyUpta 1ocuhGyK4QQzl6XOa2Ym001XyszSZaKYmVhWVq4LhprlZkK5No+C337v/3me9+WBP4XJugh/ 6nRSCq9MUiQwpAQ3dcz0bNKHbIwK1tzzYbN7OkVsl2UcZ/M+2UjWadJibL99gmQzKh0Yq9GW iVmtpVvMvnpUSLLfSv5gYRKuxVGMc2bdezF3W11AcIZqDcm9G2gmuUbHR4IbzrKKuN+GFYeo 4xJ5LJ9wOo1Xbgk9KYmftGViZ5ukF778aCeuoGFJJvKkgN4OHRWjeCaSUDK6CkFPxjQpDFMI huqqCGH4jSCropdciORMl4kFoRJBweCH+fwYAu2LKuR2+bhcteWtmJt96VXwerplzoTRahH0 X22YE0h6PfyrfzO3VkqHQm/OrbkwTq+BkVwt4ealdCTMFGvmPd7QWWDD3exJb4PG7PciN2N0 MDzTFxICB0DjWCEmsB+8tRWJ3IeB/iyGkqxJl0C5hn1gqwGhjg+MWhvEAi8Hp7lIJPBlGK66 jglZNQJjnRkThBB4an1JCBwO+ulSXNjpBYNj3sJdL8g15c+fkoI6Qya4A2G42zi/xQ/Ke+1k DmJ0i5rpFrXRLWqjW9SmGOHVyI9PVSXG8aqtSfz5zSpFoio1KW7zqeREA3J9sa5Z668mZO+L aUM0hZgl0rDYoCgZoUhTpSe2IaAwxle6x+56ksYq0i/yyuRoZWoCr2pDyyic8ZNe8vh4QkbH KVL4Mzx/llcuqCLK0/8K0rWvDdvtEdhsztZfM02tjqkOuhYhL+3YO+j/oMIwNRJzzPK4rO9m TeRA0LlLwJi/3/n5ZuhJr/1AtNWRpTji3PlQvi3D6LkutLW2vivgBhM9K9ZP7rg7Lres7Isb MB90GvN3HW6CEWPf3/sRyfKhkK/BjqPPGSU+EbY/jzOFOxlcFa/YugFTqhT/AblKCAleAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrDIsWRmVeSWpSXmKPExsVy+t/xu7oLrXViDZZ0Klv0njvJZHF6/zsW i6kPn7BZ/N82kdniytf3bBZty78xW3ROXMJuMXH/WXaLy7vmsFk8X/iD2YHLY++3BSweO2fd ZfeY3TGT1WPTqk42jzvX9rB5bP/2gNXjfvdxJo/Pm+QCOKL0bIryS0tSFTLyi0tslaINLYz0 DC0t9IxMLPUMjc1jrYxMlfTtbFJSczLLUov07RL0Mj4+6WIu2MFb8fT1UdYGxvtcXYycHBIC JhITvi9h72Lk4hASWMoo0XVnLSNEQlxi9/y3zBC2sMSfa11sEEWvGSVmXQbp4OQQBupet/QA WJGIgLLE1e97WUCKmAU6mCRerHvECNFxmkniQvtWVpAqNgFNib+bb7KB2LwCdhIXJswAW8ci oCrxeNJEoBoODlGBMImjJ/IgSgQlTs58wgJicwoYSWzvvcsEYjML6EnsuP6LFcKWl9j+dg4z hC0ucevJfKYJjEKzkLTPQtIyC0nLLCQtCxhZVjGKpJYW56bnFhvpFSfmFpfmpesl5+duYgTG 7LZjP7fsYOx6F3yIUYCDUYmH1yFFO1aINbGsuDL3EKMEB7OSCK/tV6AQb0piZVVqUX58UWlO avEhRlOg3yYyS4km5wPTSV5JvKGpobmFpaG5sbmxmYWSOG+HwMEYIYH0xJLU7NTUgtQimD4m Dk6pBsYy0xf2J6W28L69duFiw9zZN4s2XNnbXZe/5Tm3nq4Eu0ToEb6GY6/mJa37ITT7UF+P XX3n+WNFtUkrmHNkp1T4zWBv2BOtxK7u8s5x9abtd2tOaYjU741wVo2cOLmEl/F45cOHslq8 TirfXokHTn054dj9E7w/v8fJsEbsUPjGd09MtnSa9BMlluKMREMt5qLiRAAFCI9Z7wIAAA== X-CMS-MailID: 20190715083857eucas1p272d8e645daa15994fff794dbf7c26841 X-Msg-Generator: CA X-RootMTR: 20190706010615epcas2p343102f858a7fadaf6785f7ece105f1a7 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20190706010615epcas2p343102f858a7fadaf6785f7ece105f1a7 References: <20190703214326.41269-1-jeffrey.l.hugo@gmail.com> <20190703214512.41319-1-jeffrey.l.hugo@gmail.com> <20190706010604.GG20625@sirena.org.uk> <64ca3a74-374f-d4f3-bee6-a607cc5c0fc5@samsung.com> <20190711145045.GI14859@sirena.co.uk> Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 11.07.2019 16:50, Mark Brown wrote: > On Thu, Jul 11, 2019 at 03:11:56PM +0200, Andrzej Hajda wrote: > >> 1. DSI protocol defines actually more than 30 types of transactions[1], >> but this patchset implements only few of them (dsi generic write/read >> family). Is it possible to implement multiple types of transactions in >> regmap? > You can, there's a couple of different ways depending on how > exactly things are done. > >> 3. DSI devices are no MFDs so regmap abstraction has no big value added >> (correct me, if there are other significant benefits). > There's a few extra bits even if you're not using the marshalling > code to get things onto the bus - the main ones are the register > cache support (which people often use for simpler suspend/resume > support) and the debug and trace facilities (things like > tracepoints and debugfs for dumping the register map). I do not see cache usable in bridge drivers, I guess default config will be caching disabled, as it is already in the driver from this patchset. So beside marshaling, we are left only with debug facilities, not a big gain :) Moreover as it was already written DSI is mainly used to transport COMMANDS to the device, with variable number of arguments - it does not resembles registry map at all. On the other side there is some subset of DSI devices which exposes register memory using MIPI DSI Generic Write/Read packets, for example: ti-sn65dsi86, tc358764. They fit better to regmap framework. Hard to say how common is this pattern. Maybe we can try with it? If yes it would be good to put clear remark that regmap/dsi is for such devices, to avoid possible confusion. Regards Andrzej