Re: LDD3 vs Essential Linux Device Drivers
On Fri, May 01, 2020 at 07:58:11AM +0200, Mohamed Dawod wrote: > Hi, > > I would like to start learning about Linux kernel and device drivers > development. > Should I have to start with LDD3 as a lot of people advice ? or can I start > with the Essential Linux Device Drivers by Sreekrishnan Venkateswaran. > I know that the second book may be more advanced but I feel that it's more > more practical and easier to be understood. Why not get both and see which one works for you? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
LDD3 vs Essential Linux Device Drivers
Hi, I would like to start learning about Linux kernel and device drivers development. Should I have to start with LDD3 as a lot of people advice ? or can I start with the Essential Linux Device Drivers by Sreekrishnan Venkateswaran. I know that the second book may be more advanced but I feel that it's more more practical and easier to be understood. Thanks, -- Mohamed ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: how to perform i2c transaction with disabled irq?
They are afraid that some peripheral device will report interrupt and after board reset the peripheral device will be in some transient state if handling of interrupt from peripheral device will be somewhere in the middle interrupted by board reset. However in this case this is probably uboot task to initialize peripheral devices from the beginning, switch them and release from reset. Or another way is to shutdown peripheral devices before reset, disable interrupts in their internal registers - at least when /sbin/reboot is executed we see that before reset shutdown procedure is running. On Thu, Apr 30, 2020 at 1:20 PM Greg KH wrote: > On Thu, Apr 30, 2020 at 01:11:06PM +0200, Tomek The Messenger wrote: > > Hi > > If I don't have disabled irqs I can use API i2c_smbus_write_byte in order > > to perform i2c transaction. > > But how to make i2c transaction if I have disabled irq? Is any built-in > > function which lets such operation, where there is some polling > implemented? > > The background is that I do i2c transaction in restart handler (some i2c > > transaction to hot swap controller) in order to reset board. And linux > > before entering restart handler list disable interrupts. There is a > > function to enable back interrupts but in company in which I am working > > engineers reviewed it and said "it is not allowed, restart must be > > performed when interrupts are disabled". > > Ask the engineers how you are supposed to use an interrupt driven device > with interrupts disabled. > > good luck! > > greg k-h > ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Call flush_scheduled_work in the context of a work routine
The comment to flush_scheduled_work states that calling this function in
the context of a work routine will lead to deadlock. I think it means
following scenario:
static void
handler(struct work_struct *work)
{
flush_scheduled_work();
}
static DECLARE_WORK(work, handler);
schedule_work(&work);
If this is true for system workqueue (system_wq) is it also applied to
custom workqueue? I want to wait for completion of the workqueues in
another workqueue. For example:
static void
handler(struct work_struct *work)
{
struct work_data * data = (struct work_data *)work;
flush_scheduled_work();
kfree(data);
}
wq = create_workqueue("wq_test");
data = kmalloc(sizeof(struct work_data), GFP_KERNEL);
INIT_WORK(&data->work, handler);
queue_work(wq, &data->work);
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Re: how to perform i2c transaction with disabled irq?
On Thu, Apr 30, 2020 at 01:11:06PM +0200, Tomek The Messenger wrote: > Hi > If I don't have disabled irqs I can use API i2c_smbus_write_byte in order > to perform i2c transaction. > But how to make i2c transaction if I have disabled irq? Is any built-in > function which lets such operation, where there is some polling implemented? > The background is that I do i2c transaction in restart handler (some i2c > transaction to hot swap controller) in order to reset board. And linux > before entering restart handler list disable interrupts. There is a > function to enable back interrupts but in company in which I am working > engineers reviewed it and said "it is not allowed, restart must be > performed when interrupts are disabled". Ask the engineers how you are supposed to use an interrupt driven device with interrupts disabled. good luck! greg k-h ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
how to perform i2c transaction with disabled irq?
Hi If I don't have disabled irqs I can use API i2c_smbus_write_byte in order to perform i2c transaction. But how to make i2c transaction if I have disabled irq? Is any built-in function which lets such operation, where there is some polling implemented? The background is that I do i2c transaction in restart handler (some i2c transaction to hot swap controller) in order to reset board. And linux before entering restart handler list disable interrupts. There is a function to enable back interrupts but in company in which I am working engineers reviewed it and said "it is not allowed, restart must be performed when interrupts are disabled". ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
