Commit bc4a09d8 authored by Stanley Chu's avatar Stanley Chu Committed by Alexandre Belloni
Browse files

i3c: master: svc: Fix npcm845 FIFO_EMPTY quirk 



In a private write transfer, the driver pre-fills the FIFO to work around
the FIFO_EMPTY quirk. However, if an IBIWON event occurs, the hardware
emits a NACK and the driver initiates a retry. During the retry, driver
attempts to pre-fill the FIFO again if there is remaining data, but since
the FIFO is already full, this leads to data loss.

Check available space in FIFO to prevent overflow.

Fixes: 4008a74e ("i3c: master: svc: Fix npcm845 FIFO empty issue")
Signed-off-by: default avatarStanley Chu <yschu@nuvoton.com>
Link: https://lore.kernel.org/r/20250730003719.1825593-1-yschu@nuvoton.com


Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent d028219a

drivers/i3c/master/svc-i3c-master.c

+14 −8
Original line number Diff line number Diff line
@@ -104,6 +104,7 @@ 
#define   SVC_I3C_MDATACTRL_TXTRIG_FIFO_NOT_FULL GENMASK(5, 4)

#define   SVC_I3C_MDATACTRL_RXTRIG_FIFO_NOT_EMPTY 0

#define   SVC_I3C_MDATACTRL_RXCOUNT(x) FIELD_GET(GENMASK(28, 24), (x))

#define   SVC_I3C_MDATACTRL_TXCOUNT(x) FIELD_GET(GENMASK(20, 16), (x))

#define   SVC_I3C_MDATACTRL_TXFULL BIT(30)

#define   SVC_I3C_MDATACTRL_RXEMPTY BIT(31)
@@ -1304,15 +1305,20 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master, 
		 * FIFO start filling as soon as possible after EmitStartAddr.

		 */

		if (svc_has_quirk(master, SVC_I3C_QUIRK_FIFO_EMPTY) && !rnw && xfer_len) {

			u32 end = xfer_len > SVC_I3C_FIFO_SIZE ? 0 : SVC_I3C_MWDATAB_END;

			u32 len = min_t(u32, xfer_len, SVC_I3C_FIFO_SIZE);

			u32 space, end, len;



			reg = readl(master->regs + SVC_I3C_MDATACTRL);

			space = SVC_I3C_FIFO_SIZE - SVC_I3C_MDATACTRL_TXCOUNT(reg);

			if (space) {

				end = xfer_len > space ? 0 : SVC_I3C_MWDATAB_END;

				len = min_t(u32, xfer_len, space);

				writesb(master->regs + SVC_I3C_MWDATAB1, out, len - 1);

				/* Mark END bit if this is the last byte */

				writel(out[len - 1] | end, master->regs + SVC_I3C_MWDATAB);

				xfer_len -= len;

				out += len;

			}

		}



		ret = readl_poll_timeout(master->regs + SVC_I3C_MSTATUS, reg,

				 SVC_I3C_MSTATUS_MCTRLDONE(reg), 0, 1000);