| Message ID | 1629132650-26277-1-git-send-email-sbhanu@codeaurora.org (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [V1] arm64: dts: qcom: sc7180: Use maximum drive strength values for eMMC | expand |
Hi, On Mon, Aug 16, 2021 at 9:51 AM Shaik Sajida Bhanu <sbhanu@codeaurora.org> wrote: > > The current drive strength values are not sufficient on non discrete > boards and this leads to CRC errors during switching to HS400 enhanced > strobe mode. > > Hardware simulation results on non discrete boards shows up that use the > maximum drive strength values for data and command lines could helps > in avoiding these CRC errors. > > So, update data and command line drive strength values to maximum. > > Signed-off-by: Shaik Sajida Bhanu <sbhanu@codeaurora.org> > --- > arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) I found this CL because you created a bug for it (thanks!), but it would have also been nice if you had CCed some folks from Google that work on the trogdor project on your patch. > diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi > index 0f2b3c0..79d7aa6 100644 > --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi > +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi > @@ -1524,13 +1524,13 @@ ap_spi_fp: &spi10 { > pinconf-cmd { > pins = "sdc1_cmd"; > bias-pull-up; > - drive-strength = <10>; > + drive-strength = <16>; > }; > > pinconf-data { > pins = "sdc1_data"; > bias-pull-up; > - drive-strength = <10>; > + drive-strength = <16>; I could be convinced that this is the right thing to do, but I want to really make sure that it has had sufficient testing. Specifically as this patch is written we'll be updating the drive strength for all boards. Increasing the drive strength can sometimes introduce new problems (reflections, noise, ...) so we have to be confident that we're not breaking someone that used to work by increasing the drive strength here. How much has this been tested? From the discussions in the bugs, it seemed like the increased drive strength was only needed for one eMMC part and that eMMC part still had problems even after the increased drive strength, it just had fewer problems. It would be good to confirm that I got my data straight, but if it's right I'd be inclined _not_ to increase the drive strength and simply to make sure we don't use that eMMC part (or solve the problems with it in a different way). I seem to remember that there were other eMMC-related values that could be set. Any chance the problems are really there? Like `fixed-emmc-driver-type`? -Doug
Hi, On Tue, Aug 17, 2021 at 6:58 AM Doug Anderson <dianders@google.com> wrote: > > > pinconf-data { > > pins = "sdc1_data"; > > bias-pull-up; > > - drive-strength = <10>; > > + drive-strength = <16>; > > I could be convinced that this is the right thing to do, but I want to > really make sure that it has had sufficient testing. Specifically as > this patch is written we'll be updating the drive strength for all > boards. Increasing the drive strength can sometimes introduce new > problems (reflections, noise, ...) so we have to be confident that > we're not breaking someone that used to work by increasing the drive > strength here. How much has this been tested? From further discussion internally, it sounds as if this should be fine and fixes more than just this one eMMC part. Thus: Reviewed-by: Douglas Anderson <dianders@chromium.org>
Bjorn, On Thu, Aug 19, 2021 at 6:44 AM Doug Anderson <dianders@google.com> wrote: > > Hi, > > On Tue, Aug 17, 2021 at 6:58 AM Doug Anderson <dianders@google.com> wrote: > > > > > pinconf-data { > > > pins = "sdc1_data"; > > > bias-pull-up; > > > - drive-strength = <10>; > > > + drive-strength = <16>; > > > > I could be convinced that this is the right thing to do, but I want to > > really make sure that it has had sufficient testing. Specifically as > > this patch is written we'll be updating the drive strength for all > > boards. Increasing the drive strength can sometimes introduce new > > problems (reflections, noise, ...) so we have to be confident that > > we're not breaking someone that used to work by increasing the drive > > strength here. How much has this been tested? > > From further discussion internally, it sounds as if this should be > fine and fixes more than just this one eMMC part. Thus: > > Reviewed-by: Douglas Anderson <dianders@chromium.org> We've been running with this patch in the Chrome OS kernel. If it looks OK to you, it'd be great for it to land in your tree. Thanks! -Doug
On Mon, 16 Aug 2021 22:20:50 +0530, Shaik Sajida Bhanu wrote: > The current drive strength values are not sufficient on non discrete > boards and this leads to CRC errors during switching to HS400 enhanced > strobe mode. > > Hardware simulation results on non discrete boards shows up that use the > maximum drive strength values for data and command lines could helps > in avoiding these CRC errors. > > [...] Applied, thanks! [1/1] arm64: dts: qcom: sc7180: Use maximum drive strength values for eMMC commit: 752432e40e8f0d02d0af07cce2d6d4b250be11ef Best regards,
diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi index 0f2b3c0..79d7aa6 100644 --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi @@ -1524,13 +1524,13 @@ ap_spi_fp: &spi10 { pinconf-cmd { pins = "sdc1_cmd"; bias-pull-up; - drive-strength = <10>; + drive-strength = <16>; }; pinconf-data { pins = "sdc1_data"; bias-pull-up; - drive-strength = <10>; + drive-strength = <16>; }; pinconf-rclk {
The current drive strength values are not sufficient on non discrete boards and this leads to CRC errors during switching to HS400 enhanced strobe mode. Hardware simulation results on non discrete boards shows up that use the maximum drive strength values for data and command lines could helps in avoiding these CRC errors. So, update data and command line drive strength values to maximum. Signed-off-by: Shaik Sajida Bhanu <sbhanu@codeaurora.org> --- arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)