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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VeDj455KpUjyGeFAvU/iNT8gTzAGIt+VE2V1K3FogGo=; b=c9XtVy/nh6Jm98rdNcYV3mgSh4cLcGK5Jg92Ymr4hCA0ZEW3llEfhH+2q+iJelbIxg gbo9UOyS1wQjFIKEqzi4nXZhY575JsiTCvPHlSoJLiLE6IRO4Z93gu9QrwhaQgXeYCRr CQpd4aEe7uwyaAzcINGq5ot4rnJJDz3CWQ8F34c0sD2QqDJq5cILP0fmKspBmcuRNVej gAxBL3Yj6xS2PTffZ7Cis9L3NsvCtIuuO/E7dZEZkT6V2s4QaItXFJmWuvck52s2qZ5x EqYpfyoNrklsmEjw8yeazTuY24g9NjEOWFrIlNxAltf8QZUlTA4/4Aaz+/uitJ2Mc2Tl Kzzw== X-Gm-Message-State: APjAAAVP+gNR74eNi7/btaMKe9tfbZUPrDi+IjwkHYrLEEL1P+EvzjFC /gVRD6lDXVjzXKef0nLWp1MTf5u5iS+erJEJ/uKZ+w== X-Google-Smtp-Source: APXvYqx84xD50NIMODd6WRKKp6Two4nx8BrixlFjO5oD+vW8e0fmtGE84cRELHAfY18BaMIh0MTDpgLtd01jmw7jVCA= X-Received: by 2002:a1f:8744:: with SMTP id j65mr43978757vkd.17.1560783563932; Mon, 17 Jun 2019 07:59:23 -0700 (PDT) MIME-Version: 1.0 References: <1560247011-26369-1-git-send-email-manish.narani@xilinx.com> <1560247011-26369-4-git-send-email-manish.narani@xilinx.com> <5feac3fb-bef3-b7d1-57d6-81e115e1f555@xilinx.com> <948514a0-e310-75fd-e8a8-6ef8bb14e41f@xilinx.com> In-Reply-To: <948514a0-e310-75fd-e8a8-6ef8bb14e41f@xilinx.com> From: Ulf Hansson Date: Mon, 17 Jun 2019 16:58:47 +0200 Message-ID: Subject: Re: [PATCH 3/3] mmc: sdhci-of-arasan: Add support for ZynqMP Platform Tap Delays Setup To: Michal Simek X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190617_075925_363048_868C7802 X-CRM114-Status: GOOD ( 17.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , DTML , rajan.vaja@xilinx.com, nava.manne@xilinx.com, "linux-mmc@vger.kernel.org" , Adrian Hunter , Linux Kernel Mailing List , Olof Johansson , Rob Herring , Manish Narani , jolly.shah@xilinx.com, Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org [...] > >> > >> > >>> In regards to the mmc data part, I suggest to drop the > >>> ->set_tap_delay() callback, but rather use a boolean flag to indicate > >>> whether clock phases needs to be changed for the variant. Potentially > >>> that could even be skipped and instead call clk_set_phase() > >>> unconditionally, as the clock core deals fine with clock providers > >>> that doesn't support the ->set_phase() callback. > >> > >> In connection to another version of this driver for latest Xilinx chip > >> it would be better to keep set_tap_delay callback in the driver. The > >> reason is that new chip/ip is capable to setup tap delays directly > >> without asking firmware to do it. That's why for versal IP there is a > >> need to call different setup_tap_delay function. > > > > The ->set_tap_delay() callback is for ZyncMp pointing to > > sdhci_arasan_zynqmp_set_tap_delay(). This function calls the > > clk_set_phase() API. > > > > What does ->set_tap_delay() do for the latest version? > > There is different set of default tap delays which should be programmed > and it is done just via writing to registers which are the part of > controller address space. Okay, I see. Not sure what makes most sense to do here, but it sounds to me like another ->set_phase() callback should be implemented for the clock provider. In other words, calling clk_set_phase() should continue to works just fine for this case as well. If it turns out to be inconvenient, we can always add the ->set_tap_delay() at a later point when it makes more sense. [...] Kind regards Uffe _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel