From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.gentoo.org (woodpecker.gentoo.org [140.211.166.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B43BB157A46; Fri, 11 Apr 2025 14:45:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=140.211.166.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744382759; cv=none; b=fjh1+/hWxg/EzDBYJa26ATvjnoWfGI2l9/6MIb5VfHrrGlJOM97WgNpkMYhSpR00z/Q2Lgh9Bd1GZMVsqptB0XOUyVTpGkIpZcpPUbIiMNAB6pP2S928zJfN3XWOtgU3DZLLEc7QQ0vWLGIzFDI+pHOD+jnVQPYqT54hrQ24O7U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744382759; c=relaxed/simple; bh=2qew7d5QYGHupMXom6yEmImq3ecfWDyQOuyLEHQb2Aw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qkMYZYJBGT8lBgHwg9VQtlSGH9li2sF/Mi7A+UQ2vJAeNKhMDwUQUqM7Kon21v8j8hC66wh21UnEf7WMHJy6uQfa9LAnQv3fs4Iqc7+hyBmfkxqQhQtB45vlpqPkZwUGtsg2tndSllb4xhAuI2cKBIj/Aj3C3OQCDLbROQj2RTg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gentoo.org; spf=pass smtp.mailfrom=gentoo.org; arc=none smtp.client-ip=140.211.166.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gentoo.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gentoo.org Received: from localhost (unknown [116.232.27.72]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dlan) by smtp.gentoo.org (Postfix) with ESMTPSA id DC77E3436BC; Fri, 11 Apr 2025 14:45:55 +0000 (UTC) Date: Fri, 11 Apr 2025 14:45:49 +0000 From: Yixun Lan To: Alex Elder Cc: Guodong Xu , ukleinek@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, p.zabel@pengutronix.de, drew@pdp7.com, inochiama@gmail.com, geert+renesas@glider.be, heylenay@4d2.org, tglx@linutronix.de, hal.feng@starfivetech.com, unicorn_wang@outlook.com, duje.mihanovic@skole.hr, linux-pwm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, spacemit@lists.linux.dev Subject: Re: [PATCH 7/9] riscv: dts: spacemit: Add PWM14 backlight support for BPI-F3 Message-ID: <20250411144549-GYA22568@gentoo> References: <20250411131423.3802611-1-guodong@riscstar.com> <20250411131423.3802611-8-guodong@riscstar.com> <20250411140510-GYA22364@gentoo> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Alex, On 09:23 Fri 11 Apr , Alex Elder wrote: > On 4/11/25 9:05 AM, Yixun Lan wrote: > > > > On 21:14 Fri 11 Apr , Guodong Xu wrote: > >> Add a PWM-based backlight node for the Banana Pi BPI-F3 board, > >> using PWM14. The backlight is defined as a 'pwm-backlight' device with > >> brightness levels and a default brightness setting. PWM14 is assigned > >> a period length of 2000 nanoseconds. > >> > >> This configuration was used to verify PWM driver changes, with PWM14 > >> tested and its waveform confirmed as correct. > >> > >> The node status is set to "disabled", and should be enabled when the > >> display driver is ready. > >> > > .. see comments below > >> Signed-off-by: Guodong Xu > >> --- > >> .../boot/dts/spacemit/k1-bananapi-f3.dts | 32 +++++++++++++++++++ > >> 1 file changed, 32 insertions(+) > >> > >> diff --git a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts > >> index 816ef1bc358e..d04b57ddeb46 100644 > >> --- a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts > >> +++ b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts > >> @@ -28,6 +28,32 @@ led1 { > >> default-state = "on"; > >> }; > >> }; > >> + > >> + pwm_bl: lcd_backlight { > >> + compatible = "pwm-backlight"; > >> + > >> + pwms = <&pwm14 2000>; > >> + brightness-levels = < > >> + 0 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 > >> + 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 > >> + 40 40 40 40 40 40 40 40 40 41 42 43 44 45 46 47 > >> + 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 > >> + 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 > >> + 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 > >> + 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 > >> + 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 > >> + 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 > >> + 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 > >> + 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 > >> + 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 > >> + 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 > >> + 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 > >> + 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 > >> + 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 > >> + >; > >> + default-brightness-level = <100>; > >> + status = "disabled"; > > I'm confused, has DT in board file with disabled status doesn't make sense? > > it doesn't really useful for placeholder, even worse that functionality may not > > verified, so I'd suggest sending along with display driver while at it.. > > I think I suggested he include this. Guodong tested PWM using > a backlight on a display connected to a Banana Pi PBI-F3 board. > The above numbers come directly from the downstream code, which > uses this PWM consistently as a display back light. > > But you're right, the exact set of numbers to use is dependent > on the display used, so it's better to add them when the display > gets integrated. > Ok > The pwm14 node could update still be added here, but that too > might as well wait until there's something to use it. So I > think this patch can just be dropped. > thanks for the explanation -- Yixun Lan (dlan) Gentoo Linux Developer GPG Key ID AABEFD55