From mboxrd@z Thu Jan 1 00:00:00 1970 From: nicolas.ferre@atmel.com (Nicolas Ferre) Date: Thu, 23 Sep 2010 10:18:21 +0200 Subject: [PATCH] at91sam9g45: fix i2c bus speed In-Reply-To: <1285147886-17100-1-git-send-email-jacmet@sunsite.dk> References: <1285147886-17100-1-git-send-email-jacmet@sunsite.dk> Message-ID: <4C9B0D4D.4050102@atmel.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Le 22/09/2010 11:31, Peter Korsgaard : > Use a correct udelay value to get bus speed around 100KHz. The udelay > value was most likely copied from the older devices, but the 9g45 > is signicantly faster (400MHz, DDR, ..), so a udelay of 2 gives a > bus speed of around 190KHz, which is too fast for some devices. > A udelay value of 5 gives a bus speed of around 90KHz here. > > Signed-off-by: Peter Korsgaard > --- > arch/arm/mach-at91/at91sam9g45_devices.c | 4 ++-- By the way, I suspect that at91sam9g20 has the same issue (400MHz core also)... We may also have a look at at91sam9g10 which embeds a 266MHz core.... [..] Best regards, -- Nicolas Ferre