6.15-stable review patch. If anyone has any objections, please let me know.
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From: Stanley Chu yschu@nuvoton.com
[ Upstream commit bc4a09d8e79cadccdd505f47b01903a80bc666e7 ]
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: 4008a74e0f9b ("i3c: master: svc: Fix npcm845 FIFO empty issue") Signed-off-by: Stanley Chu yschu@nuvoton.com Link: https://lore.kernel.org/r/20250730003719.1825593-1-yschu@nuvoton.com Signed-off-by: Alexandre Belloni alexandre.belloni@bootlin.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i3c/master/svc-i3c-master.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c index 85e16de208d3..01295eb80806 100644 --- a/drivers/i3c/master/svc-i3c-master.c +++ b/drivers/i3c/master/svc-i3c-master.c @@ -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)
@@ -1308,14 +1309,19 @@ 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); - - 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; + 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,