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by swahren
Mon Apr 08, 2019 5:42 pm
Forum: General discussion
Topic: GIVE YOUR RASPBERRY PI SD CARD A BREAK: LOG TO RAM
Replies: 19
Views: 2348

Re: GIVE YOUR RASPBERRY PI SD CARD A BREAK: LOG TO RAM

The ext4 file system already provide such a mechanism. As per default the data will be cached for 5 sec before writing. The delay is adjustable via "commit" parameter.

https://www.kernel.org/doc/Documentatio ... s/ext4.txt
by swahren
Sat Apr 06, 2019 5:07 pm
Forum: Troubleshooting
Topic: TP link Archer T2U AC600 not working
Replies: 12
Views: 558

Re: TP link Archer T2U AC600 not working

This may help unless someone comes up with a better fix as it’s a bit old https://askubuntu.com/questions/674116/how-to-install-tp-link-t2uh-wireless-adapter-driver-ralink-mt7610u The usb ID from the report is a solid match though the model is different. No, please don't do this. The driver is avai...
by swahren
Fri Mar 29, 2019 5:23 pm
Forum: Linux Kernel
Topic: Is mainline kernel perfectly good for Raspberry Pi 3 B+?
Replies: 8
Views: 1139

Re: Is mainline kernel perfectly good for Raspberry Pi 3 B+?

Do I still need to use https://github.com/raspberrypi/linux? No, you don't have to, but it isn't perfectly good. At the end this comes to a more philosophical question, what is perfect. The advantage of a vendor tree is to hack a lot of optimizations for your target device, which will never accepta...
by swahren
Mon Mar 25, 2019 8:57 pm
Forum: Advanced users
Topic: GPIO c/c++ static library
Replies: 2
Views: 275

Re: GPIO c/c++ static library

According to the configure help the libgpiod should be able to build static:
https://git.kernel.org/pub/scm/libs/lib ... gpiod.git/

This requires the GPIO character device interface.
by swahren
Tue Feb 26, 2019 8:21 pm
Forum: Advanced users
Topic: Moving Linux kernel to 4.19
Replies: 232
Views: 63384

Re: Moving Linux kernel to 4.19

Because of the many complains about broken AP mode, i want to link to my post from November: https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=224931&start=25#p1396409 Since this won't be fixed in mainline, we have two options: 1) update hostapd to a more recent version (e.g. from Buster) 2) r...
by swahren
Sat Jan 26, 2019 1:10 pm
Forum: Advanced users
Topic: Reset i2c bus?
Replies: 1
Views: 533

Re: Reset i2c bus?

Method 1 is called I2C recovery in the Linux kernel. Unfortunately the i2c driver for bcm2835 doesn't implement this feature yet.

https://www.kernel.org/doc/html/v4.19/d ... overy_info
by swahren
Sat Dec 15, 2018 3:26 pm
Forum: Advanced users
Topic: Where is the git repo with commits for VC4 death spiral?
Replies: 3
Views: 589

Re: Where is the git repo with commits for VC4 death spiral?

The author of the DMA pool patch didn't had the time to upstream the patch. But i could prepare a upstream git repo for testing.
by swahren
Fri Dec 14, 2018 6:12 pm
Forum: Device Tree
Topic: Review: Upstream RPI 3 A+ DTS
Replies: 1
Views: 1829

Review: Upstream RPI 3 A+ DTS

Hi,
since the RPI 3 A+ was released to late for Upstream Linux 4.21/5.0, i don't want to miss the next merge window for device tree sources.

So i would be glad to get a short review of this patch:
ARM: dts: add Raspberry Pi 3 A+

Regards Stefan
by swahren
Sun Dec 09, 2018 1:27 pm
Forum: Compute Module
Topic: eMMC flash memory reliability
Replies: 12
Views: 4889

Re: eMMC flash memory reliability

But how can we know for sure that eMMC really uses MLC (or maybe eMLC) and SD cards use TLC? Couldn't find any information about that. Just look at the part number of the eMMC chip and search for the datasheet. Btw there are also SLC SD cards, but they are very expensive and have a very low density...
by swahren
Sun Nov 25, 2018 12:45 pm
Forum: Advanced users
Topic: Moving Linux kernel to 4.19
Replies: 232
Views: 63384

Re: Moving Linux kernel to 4.19

Hi, this weekend i wanted to setup an access point on my Raspberry Pi 3 A+ using builtin wifi with a recent kernel. Unfortunately the hostapd 2.4 shipped with Raspbian Stretch failed with Linux 4.18 and newer: rfkill: initial event: idx=0 type=2 op=0 soft=0 hard=0 rfkill: initial event: idx=1 type=1...
by swahren
Sun Oct 28, 2018 1:30 pm
Forum: Advanced users
Topic: Using available kernel driver instead of user-space driver?
Replies: 5
Views: 1025

Re: Using available kernel driver instead of user-space driver?

Also, how would I proceed for hwmon drivers, for example. INA2xx ? Linux driver are available for that one as well, but there appears to be no dtoverlay for it. Unfortunately usually it isn't that simple. But you already located the most important part: the driver. Devices which doesn't have a plug...
by swahren
Sun Oct 14, 2018 10:13 am
Forum: Debian
Topic: Upstream driver snd-bcm2835
Replies: 8
Views: 6671

Re: Upstream driver snd-bcm2835

Hi evasjo, yes it's true that snd-bcm2835 is in staging, but there are reasons for this. One of them is the question how should the driver be probed. In the Foundation kernel this is done by devicetree, which has been rejected mainline for devices connected via firmware. Im currently working on this...
by swahren
Sat Sep 15, 2018 1:57 pm
Forum: Linux Kernel
Topic: Vanilla 4.14.67 and Raspberry Pi Kernel 4.14.67
Replies: 2
Views: 5985

Re: Vanilla 4.14.67 and Raspberry Pi Kernel 4.14.67

What are the differences between Vanilla Kernel 4.14.67 and current Raspberry Pi Kernel 4.14.67 ? Is there a list ? There is no complete list, because developers are lazy and don't waste their time with such documentation :D But can look at this to get an idea of the differences. Btw it doesn't mak...
by swahren
Thu May 17, 2018 4:16 pm
Forum: Device Tree
Topic: Review: eMMC part on CM1
Replies: 11
Views: 1663

Re: Review: eMMC part on CM1

This statement has nothing to do with changeable voltages.

Regarding to my understanding:
Raspberry Pi 3 B SD IO voltage: fixed 3.3V
Raspberry Pi CM1 MMC IO voltage: fixed 1.8V

Per default MMC core assumes a IO voltage of 3.3V. My devicetree source provides the correct, fixed IO voltage.
by swahren
Thu May 17, 2018 2:10 pm
Forum: Device Tree
Topic: Review: eMMC part on CM1
Replies: 11
Views: 1663

Re: Review: eMMC part on CM1

I never said it's changeable. There are example boards like sun7i-a20-olinuxino-lime2-emmc.dts which uses a fixed regulator as vqmmc-supply.
by swahren
Thu May 17, 2018 1:47 pm
Forum: Device Tree
Topic: Review: eMMC part on CM1
Replies: 11
Views: 1663

Re: Review: eMMC part on CM1

Without providing a fixed regulator the MMC core doesn't have any chance to know the IO line power and assume 3.3 V. This is correct for most of the Raspberry Pis except the Compute Modules.
by swahren
Thu May 17, 2018 1:31 pm
Forum: Device Tree
Topic: Review: eMMC part on CM1
Replies: 11
Views: 1663

Re: Review: eMMC part on CM1

As a software guy i'm not really familiar with reading schematics. But the regulators do match?
by swahren
Thu May 17, 2018 1:09 pm
Forum: Device Tree
Topic: Review: eMMC part on CM1
Replies: 11
Views: 1663

Re: Review: eMMC part on CM1

What is your intention with the EMMC pwrseq support? * The simple eMMC hardware reset provider The purpose of this driver is to perform standard eMMC hw reset procedure, as described by Jedec 4.4 specification. This procedure is performed just after MMC core enabled power to the given mmc host (to ...
by swahren
Thu May 17, 2018 12:41 pm
Forum: Device Tree
Topic: Review: eMMC part on CM1
Replies: 11
Views: 1663

Review: eMMC part on CM1

Hi, i'm working on the DTS for Compute Module 1 + IO board for Linux Mainline. Based on the datasheet and the schematics i created the following source and i would appreciate a review: // SPDX-License-Identifier: GPL-2.0 /dts-v1/; #include "bcm2835.dtsi" #include "bcm2835-rpi.dtsi" / { emmc_pwrseq: ...
by swahren
Sun Apr 29, 2018 9:38 am
Forum: Linux Kernel
Topic: Interrupt differences between 32-bit and 64-bit kernels
Replies: 2
Views: 6177

Re: Interrupt differences between 32-bit and 64-bit kernels

As you noticed the smp_affinity isn't implemented yet. The difference in the behaviour comes from this patch:

https://github.com/raspberrypi/linux/co ... a99570d782
by swahren
Sun Apr 29, 2018 9:22 am
Forum: Device Tree
Topic: Device Tree Overlays Using New libgpiod API?
Replies: 3
Views: 1962

Re: Device Tree Overlays Using New libgpiod API?

The new GPIO device is intended for userspace not devicetree. I'm not sure what you are trying to achieve, but this could be helpful links: gpio-line-name definition in upstream RPI 1 B: https://github.com/raspberrypi/linux/blob/rpi-4.14.y/arch/arm/boot/dts/bcm2835-rpi-b.dts#L29 GPIO binding documen...
by swahren
Sat Feb 03, 2018 9:40 am
Forum: Linux Kernel
Topic: kernel from kernel.org for raspberry pi 3
Replies: 3
Views: 7365

Re: kernel from kernel.org for raspberry pi 3

I dislike the elinux upstream guide because it's more confusing and complicated (U-Boot is not necessary). I suggest to use a default raspbian stretch lite, add the upstream DT blob and replace the kernel7.img with your build zImage. In order to use the upstream DT blob you will need to modify the c...
by swahren
Wed Dec 27, 2017 1:41 pm
Forum: Linux Kernel
Topic: Optimize Arasan SDHCI driver
Replies: 0
Views: 5785

Optimize Arasan SDHCI driver

Hi,
i currently try to optimize the Arasan SDHCI driver in Linux Mainline especially for the CM1/CM3.

According the BCM2835 datasheet the SDHCI controller should support eMMC double data rate (DDR). Is this correct?

Are there any information about enabling DDR mode?
by swahren
Tue Nov 14, 2017 8:26 pm
Forum: Linux Kernel
Topic: Differences between a Generic Linux Kernel and a Raspberry Kernel
Replies: 8
Views: 7719

Re: Differences between a Generic Linux Kernel and a Raspberry Kernel

Hmm, someone tried to get the bcm2835-sdhost driver into the mainline kernel but the main issue is that the existing driver is quite out of date. There are multiple MMC drivers, which could be very confusing. Which driver is quite out of date (sdhci-bcm2835 or bcm2835 aka sdhost)? sdhci-bcm2835 has...
by swahren
Mon Nov 13, 2017 8:20 pm
Forum: Linux Kernel
Topic: Differences between a Generic Linux Kernel and a Raspberry Kernel
Replies: 8
Views: 7719

Re: Differences between a Generic Linux Kernel and a Raspberry Kernel

This should work, maybe you need to specify the upstream device tree blob in the config.txt.

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