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[209.85.222.47]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-55cf5186d0csm336756e0c.20.2025.11.27.00.37.16 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 Nov 2025 00:37:16 -0800 (PST) Received: by mail-ua1-f47.google.com with SMTP id a1e0cc1a2514c-9372164d768so1123924241.0 for ; Thu, 27 Nov 2025 00:37:16 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCUjCCNNJ0sVzhE2T7v+sE4hRVuyp0d602opcYq8opplqEcHtRYik51dQyinEpY87E/NVmYAMZuFJ0At@lists.linux-m68k.org X-Received: by 2002:a05:6102:1623:b0:5db:e32d:a3ff with SMTP id ada2fe7eead31-5e1c41a822amr12513289137.19.1764232635987; Thu, 27 Nov 2025 00:37:15 -0800 (PST) Precedence: bulk X-Mailing-List: linux-m68k@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20251126-b4-m5441x-add-rng-support-v4-0-5309548c9555@yoseli.org> <20251126-b4-m5441x-add-rng-support-v4-1-5309548c9555@yoseli.org> In-Reply-To: From: Geert Uytterhoeven Date: Thu, 27 Nov 2025 09:37:05 +0100 X-Gmail-Original-Message-ID: X-Gm-Features: AWmQ_bkVv9s4nivghVE7rDnIpugWqg40dFmqyxV-7HzaTJ-oT-X1ymFUQxkCVvQ Message-ID: Subject: Re: [PATCH v4 1/2] hwrng: imx-rngc: Use optional clock To: Martin Kaiser Cc: Jean-Michel Hautbois via B4 Relay , Greg Ungerer , Olivia Mackall , Herbert Xu , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Jean-Michel Hautbois , Frank Li Content-Type: text/plain; charset="UTF-8" Hi Martin, On Wed, 26 Nov 2025 at 21:30, Martin Kaiser wrote: > Thus wrote Jean-Michel Hautbois via B4 Relay (devnull+jeanmichel.hautbois.yoseli.org@kernel.org): > > > From: Jean-Michel Hautbois > > > Change devm_clk_get() to devm_clk_get_optional() to support platforms > > where the RNG clock is always enabled and not exposed via the clock > > framework (such as ColdFire MCF54418). > > > Reviewed-by: Frank Li > > Signed-off-by: Jean-Michel Hautbois > > --- > > drivers/char/hw_random/imx-rngc.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c > > index 241664a9b5d9..d6a847e48339 100644 > > --- a/drivers/char/hw_random/imx-rngc.c > > +++ b/drivers/char/hw_random/imx-rngc.c > > @@ -259,7 +259,7 @@ static int __init imx_rngc_probe(struct platform_device *pdev) > > if (IS_ERR(rngc->base)) > > return PTR_ERR(rngc->base); > > > - rngc->clk = devm_clk_get(&pdev->dev, NULL); > > + rngc->clk = devm_clk_get_optional(&pdev->dev, NULL); > > if (IS_ERR(rngc->clk)) > > return dev_err_probe(&pdev->dev, PTR_ERR(rngc->clk), "Cannot get rng_clk\n"); > > The clock is not optional on a standard imx25 system. If it's missing in the > device tree, the rngb will not work and we should not load the driver. As the clocks property is marked required in Documentation/devicetree/bindings/rng/imx-rng.yaml, "make dtbs_check" should flag a missing clock. > Should we call devm_clk_get or devm_clk_get_optional, depending on the > detected device? That can quickly lead to complex code. Nowadays it is fine to rely on "make dtbs_check" for some part of the validation. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds