@@ -1176,25 +1176,29 @@ static int img_i2c_init(struct img_i2c *i2c)
((bitrate_khz * clk_period) / 2))
int_bitrate++;
- /* Setup TCKH value */
- tckh = DIV_ROUND_UP(timing.tckh, clk_period);
+ /*
+ * Setup clock duty cycle, start with 50% and adjust TCKH and TCKL
+ * values from there if they don't meet minimum timing requirements
+ */
+ tckh = int_bitrate / 2;
+ tckl = int_bitrate - tckh;
- if (tckh > 0)
- data = tckh - 1;
- else
- data = 0;
+ /* Adjust TCKH and TCKL values */
+ data = DIV_ROUND_UP(timing.tckl, clk_period);
- img_i2c_writel(i2c, SCB_TIME_TCKH_REG, data);
+ if (tckl < data) {
+ tckl = data;
+ tckh = int_bitrate - tckl;
+ }
- /* Setup TCKL value */
- tckl = int_bitrate - tckh;
+ if (tckh > 0)
+ --tckh;
if (tckl > 0)
- data = tckl - 1;
- else
- data = 0;
+ --tckl;
- img_i2c_writel(i2c, SCB_TIME_TCKL_REG, data);
+ img_i2c_writel(i2c, SCB_TIME_TCKH_REG, tckh);
+ img_i2c_writel(i2c, SCB_TIME_TCKL_REG, tckl);
/* Setup TSDH value */
tsdh = DIV_ROUND_UP(timing.tsdh, clk_period);
This is a note to let you know that I have just added a patch titled i2c: img-scb: fix LOW and HIGH period values for the SCL clock to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 3a17e197e84c1c1acc2bd77eeb13a67034529a1a Mon Sep 17 00:00:00 2001 From: Sifan Naeem <sifan.naeem@imgtec.com> Date: Thu, 10 Sep 2015 15:50:04 +0100 Subject: i2c: img-scb: fix LOW and HIGH period values for the SCL clock commit 987008dbc48479af250cddda7f36e920a47ef54f upstream. Currently, after determining the minimum value for the High period (TCKH) the remainder of the internal clock pulses is set as the Low period (TCKL). This causes the i2c clock duty cycle to be much less than 50%. Modify the starting position to TCKH and TCKL at 50% of the internal clock, and adjusts the TCKH and TCKL values from there should the minimum value for TCKL not be met. This results in duty cycles closer to 50%. Fixes: commit 27bce457d588 ("i2c: img-scb: Add Imagination Technologies I2C SCB driver") Signed-off-by: Sifan Naeem <sifan.naeem@imgtec.com> Acked-by: James Hogan <james.hogan@imgtec.com> Reviewed-by: James Hartley <james.hartley@imgtec.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/i2c/busses/i2c-img-scb.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) -- 1.9.1