From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Babic Date: Tue, 1 Dec 2015 16:07:02 +0100 Subject: [U-Boot] [PATCH] ARM: mxs: fix VDDD brownout setting In-Reply-To: <1447624032-16503-1-git-send-email-mhei@heimpold.de> References: <1447624032-16503-1-git-send-email-mhei@heimpold.de> Message-ID: <565DB796.8070707@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 15/11/2015 22:47, Michael Heimpold wrote: > At the moment, the desired brownout is at 1.0V. However, > this setting cannot be realized by hardware since we have > only 3 bits to represent the voltage difference from the > target value. > > Target value is 1500 mV, brownout target is 1000 mV, > voltage steps are 25 mV. > > Register content calculation: > (1500 [mV] - 1000 [mV]) / 25 [mV] = 20 (decimal) = 0x14 > > Register takes only 3 bits, that is 0x4. > > But 0x4 * 25 [mV] = 100 [mV], that means that actual > brownout level is 1500 [mV] - 100 [mV] = 1.4 V. > > Minimum possible BO level is > 1500 [mV] - 0x7 * 25 [mV] = 1315 [mV]. > > So lets use this value as desired BO value (which is > also the same as FSL bootlets use). > > Signed-off-by: Michael Heimpold > Cc: Marek Vasut > Cc: Otavio Salvador > Cc: Fabio Estevam > --- Applied to u-boot-imx, thanks! Best regards, Stefano Babic -- ===================================================================== DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de =====================================================================