From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2A0EA30C343; Mon, 17 Nov 2025 10:57:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763377055; cv=none; b=FgdQIN1P00LQt/gvE37hBOX40OsgVNUoKRRWCCXOz9Lv10pDxtS3Q0sJ9U7QhoqBB7UvZ1iZzZtMegNAFJ5VtWYc2T02l6sDoaSAAVOSxFsM/9AFGzYZAhJzbaNnB3QEJ+ci82IbP+mfNXokSfskQprnCgFd4CDWUqnZoZfhwRU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763377055; c=relaxed/simple; bh=3RsdR1HaRwt736EY0czV1I955a+QQs/ZdNqAwtZD+Yc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=t+KQ54Iq23aprPY8JrJOk/4Y/sBgKOul533Hdw0E2PNbHnK4U4DNWKax+WJXM8Z4UjSzoa2vUqDcfw+cTu3aT36NcIhtu8p6ooEPtTtDueJcmtuzM+OfGCacq8tsUqDxkA5o9yoNxlXY4BJOIT1uXmDyNohfp8ls/ehAgnUyXQg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cw+BPFDh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cw+BPFDh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA245C4CEF5; Mon, 17 Nov 2025 10:57:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763377054; bh=3RsdR1HaRwt736EY0czV1I955a+QQs/ZdNqAwtZD+Yc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cw+BPFDhJYxVn9GaECyrEd/0EgSlgZkEJcvY8PRKxy3oTvik5t11eJNF1B9iaLHLM aMg7jTm/Su2cMonMGCgW+jYvPorViczo3ZbJzzaLWMzaKM2oXBNtcN5Hf9VuVi1++U WToiL0W9BgtbAl0PnHkrh85xSQO6JPHFz9+jXVPj95foFZsnqT+Zsg5WxlwrFqbYp/ qA5VHT/9t4rdOyigws/B+PCDBhmWwv6dyLZAN6YQolhnZdcDyr1nJxSGHsR61yPqyU 32aU3gUIioOiLQc59rZ0Uvg9yxXK0DlX58f9BFU66e3TYH/GaIUxm9JOoCeM0Omots tVOFh6VIuDT3w== Message-ID: <50a4b4a9-afd4-42a3-9740-5e48de312f1d@kernel.org> Date: Mon, 17 Nov 2025 11:57:29 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/3] drm: Add driver for Sitronix ST7920 LCD displays To: Iker Pedrosa , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Javier Martinez Canillas Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org References: <20251031-st7920-v4-0-35291f8076b2@gmail.com> <20251031-st7920-v4-2-35291f8076b2@gmail.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 31/10/2025 10:05, Iker Pedrosa wrote: > + > +static void st7920_hw_reset(struct st7920_device *st7920) > +{ > + if (!st7920->reset_gpio) > + return; > + > + gpiod_set_value_cansleep(st7920->reset_gpio, 0); > + usleep_range(15, 20); > + gpiod_set_value_cansleep(st7920->reset_gpio, 1); This is odd. Why are you keeping device in reset state? I don't think you tested your driver with DTS. > + msleep(40); > +} > + > + > + regmap = devm_regmap_init_spi(spi, &st7920_spi_regmap_config); > + if (IS_ERR(regmap)) > + return PTR_ERR(regmap); > + > + st7920 = devm_drm_dev_alloc(dev, &st7920_drm_driver, > + struct st7920_device, drm); > + if (IS_ERR(st7920)) > + return PTR_ERR(st7920); > + > + drm = &st7920->drm; > + > + st7920->dev = dev; > + st7920->regmap = regmap; > + st7920->spi = spi; > + st7920->device_info = device_get_match_data(dev); > + st7920->width = st7920->device_info->default_width; > + st7920->height = st7920->device_info->default_height; > + > + st7920->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); So you keep device in reset state, then why do you toggle it in st7920_hw_reset()? Remember that this is the logical, not line level. > + if (IS_ERR(st7920->reset_gpio)) { > + ret = PTR_ERR(st7920->reset_gpio); > + dev_err(dev, "Unable to retrieve reset GPIO: %d\n", ret); return dev_err_probe, didn't you get comment on that? > + return ret; > + } > + > + spi_set_drvdata(spi, st7920); > + > + ret = st7920_init_modeset(st7920); > + if (ret) > + return ret; > + > + ret = drm_dev_register(drm, 0); > + if (ret) > + return dev_err_probe(dev, ret, "DRM device register failed\n"); > + > + drm_client_setup(drm, NULL); > + Best regards, Krzysztof