From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B0E7C77B7A for ; Wed, 17 May 2023 12:57:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231582AbjEQM5I convert rfc822-to-8bit (ORCPT ); Wed, 17 May 2023 08:57:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229937AbjEQM5F (ORCPT ); Wed, 17 May 2023 08:57:05 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E50711A4 for ; Wed, 17 May 2023 05:57:03 -0700 (PDT) Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[IPv6:::1]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1pzGi5-0001Dc-5f; Wed, 17 May 2023 14:56:53 +0200 Message-ID: <1c8997c7c72143d130ebbc9ba438cebddc9d35e0.camel@pengutronix.de> Subject: Re: [PATCH V6 3/6] drm: bridge: samsung-dsim: Fetch pll-clock-frequency automatically From: Lucas Stach To: Adam Ford , dri-devel@lists.freedesktop.org Cc: Marek Vasut , Neil Armstrong , Jernej Skrabec , Robert Foss , Jonas Karlman , aford@beaconembedded.com, Frieder Schrempf , linux-kernel@vger.kernel.org, Laurent Pinchart , Andrzej Hajda , Chen-Yu Tsai , Marek Szyprowski , Jagan Teki Date: Wed, 17 May 2023 14:56:47 +0200 In-Reply-To: <20230515235713.232939-4-aford173@gmail.com> References: <20230515235713.232939-1-aford173@gmail.com> <20230515235713.232939-4-aford173@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT User-Agent: Evolution 3.46.4 (3.46.4-1.fc37) MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2a0a:edc0:0:900:1d::77 X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Adam, Am Montag, dem 15.05.2023 um 18:57 -0500 schrieb Adam Ford: > Make the pll-clock-frequency optional. If it's present, use it > to maintain backwards compatibility with existing hardware. If it > is absent, read clock rate of "sclk_mipi" to determine the rate. > Since it can be optional, change the message from an error to > dev_info. > > Signed-off-by: Adam Ford > Tested-by: Chen-Yu Tsai > Tested-by: Frieder Schrempf > Reviewed-by: Frieder Schrempf > --- > drivers/gpu/drm/bridge/samsung-dsim.c | 23 ++++++++++++++++------- > 1 file changed, 16 insertions(+), 7 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c > index bf4b33d2de76..08266303c261 100644 > --- a/drivers/gpu/drm/bridge/samsung-dsim.c > +++ b/drivers/gpu/drm/bridge/samsung-dsim.c > @@ -1712,11 +1712,11 @@ static const struct mipi_dsi_host_ops samsung_dsim_ops = { > }; > > static int samsung_dsim_of_read_u32(const struct device_node *np, > - const char *propname, u32 *out_value) > + const char *propname, u32 *out_value, bool optional) > { > int ret = of_property_read_u32(np, propname, out_value); > > - if (ret < 0) > + if (ret < 0 && !optional) > pr_err("%pOF: failed to get '%s' property\n", np, propname); > > return ret; > @@ -1726,20 +1726,29 @@ static int samsung_dsim_parse_dt(struct samsung_dsim *dsi) > { > struct device *dev = dsi->dev; > struct device_node *node = dev->of_node; > + struct clk *pll_clk; > int ret; > > ret = samsung_dsim_of_read_u32(node, "samsung,pll-clock-frequency", > - &dsi->pll_clk_rate); > - if (ret < 0) > - return ret; > + &dsi->pll_clk_rate, 1); > + > + /* If it doesn't exist, read it from the clock instead of failing */ > + if (ret < 0) { > + dev_info(dev, "Using sclk_mipi for pll clock frequency\n"); While this is certainly helpful while debugging the driver, I don't think it warrants a info print. Remove or downgrade to dev_dbg? On the other hand the changed driver behavior should be documented in the devicetree binding by moving "samsung,pll-clock-frequency" into the optional properties and spelling out which clock rate is used when the property is absent. Regards, Lucas > + pll_clk = devm_clk_get(dev, "sclk_mipi"); > + if (!IS_ERR(pll_clk)) > + dsi->pll_clk_rate = clk_get_rate(pll_clk); > + else > + return PTR_ERR(pll_clk); > + } > > ret = samsung_dsim_of_read_u32(node, "samsung,burst-clock-frequency", > - &dsi->burst_clk_rate); > + &dsi->burst_clk_rate, 0); > if (ret < 0) > return ret; > > ret = samsung_dsim_of_read_u32(node, "samsung,esc-clock-frequency", > - &dsi->esc_clk_rate); > + &dsi->esc_clk_rate, 0); > if (ret < 0) > return ret; >