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Mon, 14 Jul 2025 08:45:40 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id U6RPCbTDdGhdMwAAD6G6ig (envelope-from ); Mon, 14 Jul 2025 08:45:40 +0000 Message-ID: <10bb159a-0c6a-4950-b038-68608e2a771d@suse.de> Date: Mon, 14 Jul 2025 10:45:39 +0200 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 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional To: Javier Martinez Canillas , linux-kernel@vger.kernel.org Cc: ipedrosa@redhat.com, David Airlie , Maarten Lankhorst , Marcus Folkesson , Maxime Ripard , Simona Vetter , dri-devel@lists.freedesktop.org References: <20250710102453.101078-1-javierm@redhat.com> <20250710102453.101078-3-javierm@redhat.com> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNJ1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPsLAjgQTAQgAOAIb AwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftODH AAoJEGgNwR1TC3ojx1wH/0hKGWugiqDgLNXLRD/4TfHBEKmxIrmfu9Z5t7vwUKfwhFL6hqvo lXPJJKQpQ2z8+X2vZm/slsLn7J1yjrOsoJhKABDi+3QWWSGkaGwRJAdPVVyJMfJRNNNIKwVb U6B1BkX2XDKDGffF4TxlOpSQzdtNI/9gleOoUA8+jy8knnDYzjBNOZqLG2FuTdicBXblz0Mf vg41gd9kCwYXDnD91rJU8tzylXv03E75NCaTxTM+FBXPmsAVYQ4GYhhgFt8S2UWMoaaABLDe 7l5FdnLdDEcbmd8uLU2CaG4W2cLrUaI4jz2XbkcPQkqTQ3EB67hYkjiEE6Zy3ggOitiQGcqp j//OwE0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRHUE9eosYb T6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgTRjP+qbU6 3Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+RdhgATnWW GKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zbehDda8lv hFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r12+lqdsA EQEAAcLAdgQYAQgAIAIbDBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftOH6AAoJEGgNwR1T C3ojVSkIALpAPkIJPQoURPb1VWjh34l0HlglmYHvZszJWTXYwavHR8+k6Baa6H7ufXNQtThR yIxJrQLW6rV5lm7TjhffEhxVCn37+cg0zZ3j7zIsSS0rx/aMwi6VhFJA5hfn3T0TtrijKP4A SAQO9xD1Zk9/61JWk8OysuIh7MXkl0fxbRKWE93XeQBhIJHQfnc+YBLprdnxR446Sh8Wn/2D Ya8cavuWf2zrB6cZurs048xe0UbSW5AOSo4V9M0jzYI4nZqTmPxYyXbm30Kvmz0rYVRaitYJ 4kyYYMhuULvrJDMjZRvaNe52tkKAvMevcGdt38H4KSVXAylqyQOW5zvPc4/sq9c= In-Reply-To: <20250710102453.101078-3-javierm@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; FREEMAIL_CC(0.00)[redhat.com,gmail.com,linux.intel.com,kernel.org,ffwll.ch,lists.freedesktop.org]; MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_TLS_ALL(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; RCPT_COUNT_SEVEN(0.00)[9]; MID_RHS_MATCH_FROM(0.00)[]; TAGGED_RCPT(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO X-Spam-Level: X-Spam-Score: -2.80 Hi Am 10.07.25 um 12:24 schrieb Javier Martinez Canillas: > Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin, > so lets relax this in the driver and make the reset GPIO to be optional. > > The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but > returns NULL when there isn't a reset-gpios property defined in a DT node. > > The DT binding schema for "sitronix,st7571" that require a reset GPIO will > enforce the "reset-gpios" to be present, due being a required DT property. > But in the driver itself the property can be made optional if not defined. > > Signed-off-by: Javier Martinez Canillas > --- > > drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c > index eec846892962..73e8db25f895 100644 > --- a/drivers/gpu/drm/sitronix/st7571-i2c.c > +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c > @@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571) > st7571->nlines = dt.vactive.typ; > st7571->ncols = dt.hactive.typ; > > - st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH); > + st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); > if (IS_ERR(st7571->reset)) > - return PTR_ERR(st7571->reset); > + return dev_err_probe(dev, PTR_ERR(st7571->reset), > + "Failed to get reset gpio\n"); > > return 0; > } > > static void st7571_reset(struct st7571_device *st7571) > { > + if (!st7571->reset) > + return; > + My interpretation of this function is that calling it guarantees a device reset (or an error). So I'd push this test into the caller. Best regards Thomas > gpiod_set_value_cansleep(st7571->reset, 1); > fsleep(20); > gpiod_set_value_cansleep(st7571->reset, 0); -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)