On 08/29/2017 03:52 PM, Hans de Goede wrote:
Hi,
On 29-08-17 14:22, Andy Shevchenko wrote:
On Tue, 2017-08-29 at 14:08 +0200, Hans de Goede wrote:
The Lenovo Miix2 8 DSDT contains an i2c clk / bus speed of 1700000 Hz
for one if its devices, which is not supported.
This is the second DSDT to show up with an unsupported clk in a short
time, remove the hardcoded fix for DSDTs with a 1 MiHz clock and
simply
always round down the clk to the nearest supported value.
Reported-by: russianneuromancer@xxxxx
Fixes: 682c6c2188 ("i2c: designware: Some broken DSTDs use 1MiHz ...")
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-platdrv.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
b/drivers/i2c/busses/i2c-designware-platdrv.c
index 57248bccadbc..2b98a173136f 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -256,7 +256,8 @@ static int dw_i2c_plat_probe(struct
platform_device *pdev)
struct dw_i2c_dev *dev;
u32 acpi_speed, ht = 0;
struct resource *mem;
- int irq, ret;
+ int i, irq, ret;
+ const int supported_speeds[] = { 0, 100000, 400000, 1000000,
3400000 };
irq = platform_get_irq(pdev, 0);
if (irq < 0)
@@ -297,9 +298,16 @@ static int dw_i2c_plat_probe(struct
platform_device *pdev)
}
acpi_speed = i2c_acpi_find_bus_speed(&pdev->dev);
- /* Some broken DSTDs use 1MiHz instead of 1MHz */
- if (acpi_speed == 1048576)
- acpi_speed = 1000000;
+ /*
+ * Some DSTDs use a non standard speed, round down to the
lowest
+ * standard speed.
+ */
+ for (i = 1; i < ARRAY_SIZE(supported_speeds); i++) {
+ if (acpi_speed < supported_speeds[i])
+ break;
+ }
+ acpi_speed = supported_speeds[i - 1];
I dunno what standard says if we may or may not use 100 kHz as a last
resort even for speeds defined less than 100 kHz.
The < 100000 case is for when i2c_acpi_find_bus_speed() returns 0, so
that we then keep it 0, in which case the code a bit lower will pick
a default. Since speeds < 100000 are clearly not valid treating them
as ACPI not providing any bus-speed info seems sensible to me.
I don't know how sensible values timing parameter calculation routines
would produce for "bogus" < 100 kHz ACPI speeds so picking the default
400 kHz sounds more sensible to me as well as it used to be the default
speed earlier.
Acked-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
