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([2a01:110f:b59:fd00:e953:3254:5e71:3177]) by smtp.gmail.com with ESMTPSA id z18sm2200844ejb.92.2020.09.11.14.21.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Sep 2020 14:21:34 -0700 (PDT) Subject: Re: [PATCH v3 1/2] leds: mt6360: Add LED driver for MT6360 To: Gene Chen , Pavel Machek Cc: robh+dt@kernel.org, Matthias Brugger , Dan Murphy , linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, Gene Chen , Wilma.Wu@mediatek.com, shufan_lee@richtek.com, cy_huang@richtek.com, benjamin.chao@mediatek.com References: <1599474459-20853-1-git-send-email-gene.chen.richtek@gmail.com> <1599474459-20853-2-git-send-email-gene.chen.richtek@gmail.com> <559a568e-3a2e-33c6-43aa-547a18f8e26b@gmail.com> <20200911070503.GA9818@amd> From: Jacek Anaszewski Message-ID: <7e67c8f7-7f79-72f8-05bc-022ed0655a3f@gmail.com> Date: Fri, 11 Sep 2020 23:21:32 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 9/11/20 1:24 AM, Gene Chen wrote: > Pavel Machek 於 2020年9月11日 週五 下午3:05寫道： >> >> Hi! >> >>>> +{ >>>> + struct mt6360_led *led = container_of(lcdev, struct mt6360_led, flash.led_cdev); >>>> + struct mt6360_priv *priv = led->priv; >>>> + u32 enable_mask = MT6360_TORCHEN_MASK | MT6360_FLCSEN_MASK(led->led_no); >>>> + u32 val = (level) ? MT6360_FLCSEN_MASK(led->led_no) : 0; >>>> + u32 prev = priv->fled_torch_used, curr; >>>> + int ret; >>>> + >>>> + dev_dbg(lcdev->dev, "[%d] brightness %d\n", led->led_no, level); >>>> + if (priv->fled_strobe_used) { >>>> + dev_warn(lcdev->dev, "Please disable strobe first [%d]\n", priv->fled_strobe_used); >>> >>> Doesn't hardware handle that? IOW, what happens when you have enabled >>> both torch and flash? If flash just overrides torch mode, than you >>> should not prevent enabling torch in this case. >> >> Yep, this is strange/confusing... and was reason why I asked for not >> supporting strobe from sysfs. >> >> Could I get you to remove code you are not commenting at when >> reviewing? >> > > MT6360 FLED register define is STROBE_EN/TORCH_EN/CS1/CS2 (current > source) 4 bits. > The STROBE_EN/TORCH_EN is shared by FLED1 and FLED2. > If I want to enable FLED1 torch mode, I set TORCH_EN and CS1 > If I want to enable FLED2 strobe mode, I set STROBE_EN and CS2 > For example I set FLED1 torch, then I set FLED2 strobe. > When I set FLED2 strobe, I will see the strobe current is FLED2 add > FLED1 current which is not I want. > So I need disable FLED1 torch first. > Considering every circumstances is complicated when share same H/W > logic control. > And the other problem is torch mode switch to strobe mode needs ramp > time because strobe and torch mode can't be co-exist. Thank you for the explanation. So we have to keep your guards but I would return -EBUSY instead of -EINVAL. This would be also consistent with what drivers/media/v4l2-core/v4l2-flash-led-class.c does in its v4l2_flash_s_ctrl(), case V4L2_CID_FLASH_STROBE - it returns -EBUSY if __software_strobe_mode_inactive() returns false. The advantage of V4L2 Flash interface is that it has LED_MODE that can be set to torch or flash, but in LED subsystem we don't have the counterpart. -- Best regards, Jacek Anaszewski