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Commit 9c2baf78 authored by David Brownell's avatar David Brownell Committed by Haavard Skinnemoen
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at32ap700x spi: enable pullups on MISO 



This is a minor tweak to the at32ap700x pin configuration for the SPI
input pin (MISO), enabling the on-chip weak pullup (typical 190K) to

  (a) ensure a fixed data value for missing or input-only slaves;

  (b) prevent power waste associated with inputs floating near VDDIO/2.

Atmel's boards have no external pullup or pulldown on these pins, so
it's unlikely other boards would address these issues with external
pulldowns.  Were there trouble, board-specific code could turn off
the relevant pullup(s).

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
parent 7ef31e9c

arch/avr32/mach-at32ap/at32ap700x.c

+4 −2
Original line number Diff line number Diff line
@@ -1181,7 +1181,8 @@ at32_add_device_spi(unsigned int id, struct spi_board_info *b, unsigned int n) 
	switch (id) {

	case 0:

		pdev = &atmel_spi0_device;

		select_peripheral(PA(0),  PERIPH_A, 0);	/* MISO	 */

		/* pullup MISO so a level is always defined */

		select_peripheral(PA(0),  PERIPH_A, AT32_GPIOF_PULLUP);

		select_peripheral(PA(1),  PERIPH_A, 0);	/* MOSI	 */

		select_peripheral(PA(2),  PERIPH_A, 0);	/* SCK	 */

		at32_spi_setup_slaves(0, b, n, spi0_pins);
@@ -1189,7 +1190,8 @@ at32_add_device_spi(unsigned int id, struct spi_board_info *b, unsigned int n) 


	case 1:

		pdev = &atmel_spi1_device;

		select_peripheral(PB(0),  PERIPH_B, 0);	/* MISO  */

		/* pullup MISO so a level is always defined */

		select_peripheral(PB(0),  PERIPH_B, AT32_GPIOF_PULLUP);

		select_peripheral(PB(1),  PERIPH_B, 0);	/* MOSI  */

		select_peripheral(PB(5),  PERIPH_B, 0);	/* SCK   */

		at32_spi_setup_slaves(1, b, n, spi1_pins);