[PATCH] staging: fbtft: replace -1 with proper error codes

[Soham Kute <officialsohamkute@gmail.com>]

Replace return -1 with proper kernel error codes:
- -ENODEV when SPI device is NULL
- -EINVAL when display size or buffer is invalid
- -EOPNOTSUPP for unimplemented functions

Signed-off-by: Soham Kute <officialsohamkute@gmail.com>
---
 drivers/staging/fbtft/fb_ra8875.c | 4 ++--
 drivers/staging/fbtft/fbtft-bus.c | 4 ++--
 drivers/staging/fbtft/fbtft-io.c  | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/fbtft/fb_ra8875.c b/drivers/staging/fbtft/fb_ra8875.c
index 0ab1de6647d0..c2e5c6276415 100644
--- a/drivers/staging/fbtft/fb_ra8875.c
+++ b/drivers/staging/fbtft/fb_ra8875.c
@@ -29,7 +29,7 @@ static int write_spi(struct fbtft_par *par, void *buf, size_t len)
 	if (!par->spi) {
 		dev_err(par->info->device,
 			"%s: par->spi is unexpectedly NULL\n", __func__);
-		return -1;
+		return -ENODEV;
 	}
 
 	spi_message_init(&m);
@@ -144,7 +144,7 @@ static int init_display(struct fbtft_par *par)
 		write_reg(par, 0x1F, 0x01);
 	} else {
 		dev_err(par->info->device, "display size is not supported!!");
-		return -1;
+		return -EINVAL;
 	}
 
 	/* PWM clock */
diff --git a/drivers/staging/fbtft/fbtft-bus.c b/drivers/staging/fbtft/fbtft-bus.c
index 30e436ff19e4..9a87bddd7d19 100644
--- a/drivers/staging/fbtft/fbtft-bus.c
+++ b/drivers/staging/fbtft/fbtft-bus.c
@@ -181,7 +181,7 @@ int fbtft_write_vmem16_bus9(struct fbtft_par *par, size_t offset, size_t len)
 
 	if (!par->txbuf.buf) {
 		dev_err(par->info->device, "%s: txbuf.buf is NULL\n", __func__);
-		return -1;
+		return -EINVAL;
 	}
 
 	remain = len;
@@ -217,7 +217,7 @@ EXPORT_SYMBOL(fbtft_write_vmem16_bus9);
 int fbtft_write_vmem8_bus8(struct fbtft_par *par, size_t offset, size_t len)
 {
 	dev_err(par->info->device, "%s: function not implemented\n", __func__);
-	return -1;
+	return -EOPNOTSUPP;
 }
 EXPORT_SYMBOL(fbtft_write_vmem8_bus8);
 
diff --git a/drivers/staging/fbtft/fbtft-io.c b/drivers/staging/fbtft/fbtft-io.c
index de1904a443c2..2144f5257fa9 100644
--- a/drivers/staging/fbtft/fbtft-io.c
+++ b/drivers/staging/fbtft/fbtft-io.c
@@ -19,7 +19,7 @@ int fbtft_write_spi(struct fbtft_par *par, void *buf, size_t len)
 	if (!par->spi) {
 		dev_err(par->info->device,
 			"%s: par->spi is unexpectedly NULL\n", __func__);
-		return -1;
+		return -ENODEV;
 	}
 
 	spi_message_init(&m);
@@ -231,6 +231,6 @@ EXPORT_SYMBOL(fbtft_write_gpio16_wr);
 int fbtft_write_gpio16_wr_latched(struct fbtft_par *par, void *buf, size_t len)
 {
 	dev_err(par->info->device, "%s: function not implemented\n", __func__);
-	return -1;
+	return -EOPNOTSUPP;
 }
 EXPORT_SYMBOL(fbtft_write_gpio16_wr_latched);
-- 
2.34.1