robertlipe commented on issue #5810:
URL:
https://github.com/apache/incubator-nuttx/issues/5810#issuecomment-1077289054
If it helps, I got lost in the layering, too. I wasn't sure what was
supposed to be in kernel/"user" space and who was supposed to be able to
fondle each others' bits from any given layer in the abstraction. That's
why I called in for design guidance from those above with familiarity with
multiple subsystems.
Though I saw that ESP32-C3 got one case "more right" than BL602, I wasn't
really convinced it was the ideal role model, either. That was the point I
started chasing both ends of the candle, one up and over into
well-exercised ARM boards and generic vs. chip vs board vs any given bit
being remapped as a normal GPIO or a specialized SPIO-type pin - and if the
inversion was done within the chip itself AND learning the other end and
getting tripped up in LVGL vs. NX and a framebuffer vs. a framework and so
on as those didn't seem to have crisp edges to me. Your code had the MISO
swap and trunk didn't, so I wasn't sure it had been done in some other way,
but that was also the time I was working with your branch and not nuttx
master, so I couldn't tell if that was a design decision or just a.
dropped/unneeded/unwanted PR.
I got quite confused and had to mentally context switch away from it
for other reasons; I've not made it back since then. I hope to get back to
it in the next couple of days.
Good luck!
On Wed, Mar 23, 2022 at 9:23 PM Lee Lup Yuen ***@***.***>
wrote:
> ST7789 Driver runs in Kernel Space so I don't think it can access
> /dev/gpio*?
>
> There is a generic LCD Driver that wraps up the ST7789 Driver as /dev/lcd*
> :
>
>
>
https://github.com/lupyuen/incubator-nuttx/blob/st7789/drivers/lcd/lcd_dev.c#L342-L343
>
> I suppose LVGL runs in User Mode to access /dev/lcd*? I'm still
> deciphering the code.
>
> There's another GPIO quirk inside the SPI Driver for ESP32: To control the
> ST7789 Data/Command Pin, the SPI Driver flips the MISO Pin as though it was
> a GPIO: esp32c3_board_spi.c
>
<https://github.com/lupyuen/incubator-nuttx/blob/st7789/boards/risc-v/esp32c3/esp32c3-devkit/src/esp32c3_board_spi.c#L64-L84>
>
> int esp32c3_spi2_cmddata(FAR struct spi_dev_s *dev, uint32_t devid, bool
cmd) {
> ...
> /* This is the Data/Command control pad which determines whether
the * data bits are data or a command. */
> esp32c3_gpiowrite(CONFIG_ESP32C3_SPI2_MISOPIN, !cmd);
>
> To implement this on BL602 I'm trying to reconfigure MISO as GPIO on the
> fly: bl602_spi.c
>
<https://github.com/lupyuen/incubator-nuttx/blob/st7789/arch/risc-v/src/bl602/bl602_spi.c#L709-L735>
>
> static int bl602_spi_cmddata(struct spi_dev_s *dev, uint32_t devid, bool
cmd) {
> // MISO is now configured as SPI Pin. We reconfigure MISO as GPIO Pin.
> gpio_pinset_t gpio =
> (BOARD_SPI_MISO & GPIO_PIN_MASK) // Get the pin number
> | GPIO_OUTPUT | GPIO_PULLUP | GPIO_FUNC_SWGPIO; // Change to GPIO
Output
> int ret = bl602_configgpio(gpio);
> ...
> // Set MISO to High (data) or Low (command)
> bl602_gpiowrite(gpio, !cmd);
>
> // After this the caller will transmit data or command.
> // Then bl602_spi_select() will revert MISO back from GPIO to SPI Pin.
> // We must revert because the SPI Bus may be used by other drivers.
> return OK;
> }
>
> I'm now testing this with a Logic Analyser. I'm hitting another problem
> with SPI Receive Timeout but I'll explain later:
>
> https://github.com/lupyuen/incubator-nuttx/pull/39/files
>
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