-Remove chunk splitting in tinydrm_spi_transfer in tinydrm-helpers as The spi 
core will split a buffer into max_dma_len chunks for the
 spi controller driver to handle.
-Remove automatic byte swapping in tinydrm_spi_transfer as it doesn't have 
users.
-Remove the upper bound check on dma transfer length in bcm2835_spi_can_dma().

Signed-off-by: Meghana Madhyastha <meghana.madhyas...@gmail.com>
---
 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 48 ++++----------------------
 drivers/gpu/drm/tinydrm/mipi-dbi.c             | 10 ++----
 drivers/spi/spi-bcm2835.c                      | 15 +-------
 3 files changed, 9 insertions(+), 64 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c 
b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
index bf96072d1b97..6064099e8e63 100644
--- a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
@@ -452,62 +452,26 @@ int tinydrm_spi_transfer(struct spi_device *spi, u32 
speed_hz,
        struct spi_transfer tr = {
                .bits_per_word = bpw,
                .speed_hz = speed_hz,
+               .tx_buf = buf,
+               .len = len
        };
        struct spi_message m;
-       u16 *swap_buf = NULL;
        size_t max_chunk;
-       size_t chunk;
-       int ret = 0;
 
-       if (WARN_ON_ONCE(bpw != 8 && bpw != 16))
-               return -EINVAL;
-
-       max_chunk = tinydrm_spi_max_transfer_size(spi, 0);
+       max_chunk = SIZE_MAX;
 
        if (drm_debug & DRM_UT_DRIVER)
                pr_debug("[drm:%s] bpw=%u, max_chunk=%zu, transfers:\n",
-                        __func__, bpw, max_chunk);
-
-       if (bpw == 16 && !tinydrm_spi_bpw_supported(spi, 16)) {
-               tr.bits_per_word = 8;
-               if (tinydrm_machine_little_endian()) {
-                       swap_buf = kmalloc(min(len, max_chunk), GFP_KERNEL);
-                       if (!swap_buf)
-                               return -ENOMEM;
-               }
-       }
+                       __func__, bpw, max_chunk);
 
        spi_message_init(&m);
        if (header)
                spi_message_add_tail(header, &m);
        spi_message_add_tail(&tr, &m);
 
-       while (len) {
-               chunk = min(len, max_chunk);
-
-               tr.tx_buf = buf;
-               tr.len = chunk;
-
-               if (swap_buf) {
-                       const u16 *buf16 = buf;
-                       unsigned int i;
-
-                       for (i = 0; i < chunk / 2; i++)
-                               swap_buf[i] = swab16(buf16[i]);
-
-                       tr.tx_buf = swap_buf;
-               }
-
-               buf += chunk;
-               len -= chunk;
-
-               tinydrm_dbg_spi_message(spi, &m);
-               ret = spi_sync(spi, &m);
-               if (ret)
-                       return ret;
-       }
+       tinydrm_dbg_spi_message(spi, &m);
 
-       return 0;
+       return spi_sync(spi, &m);
 }
 EXPORT_SYMBOL(tinydrm_spi_transfer);
 
diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c 
b/drivers/gpu/drm/tinydrm/mipi-dbi.c
index 75dd65c57e74..c8af2d65c2ad 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -886,15 +886,9 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, 
u8 cmd,
 int mipi_dbi_spi_init(struct spi_device *spi, struct mipi_dbi *mipi,
                      struct gpio_desc *dc)
 {
-       size_t tx_size = tinydrm_spi_max_transfer_size(spi, 0);
        struct device *dev = &spi->dev;
        int ret;
 
-       if (tx_size < 16) {
-               DRM_ERROR("SPI transmit buffer too small: %zu\n", tx_size);
-               return -EINVAL;
-       }
-
        /*
         * Even though it's not the SPI device that does DMA (the master does),
         * the dma mask is necessary for the dma_alloc_wc() in
@@ -924,8 +918,8 @@ int mipi_dbi_spi_init(struct spi_device *spi, struct 
mipi_dbi *mipi,
                        mipi->swap_bytes = true;
        } else {
                mipi->command = mipi_dbi_typec1_command;
-               mipi->tx_buf9_len = tx_size;
-               mipi->tx_buf9 = devm_kmalloc(dev, tx_size, GFP_KERNEL);
+               mipi->tx_buf9_len = SZ_16K;
+               mipi->tx_buf9 = devm_kmalloc(dev, mipi->tx_buf9_len, 
GFP_KERNEL);
                if (!mipi->tx_buf9)
                        return -ENOMEM;
        }
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index f35cc10772f6..2fd650891c07 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -365,19 +365,6 @@ static bool bcm2835_spi_can_dma(struct spi_master *master,
        if (tfr->len < BCM2835_SPI_DMA_MIN_LENGTH)
                return false;
 
-       /* BCM2835_SPI_DLEN has defined a max transfer size as
-        * 16 bit, so max is 65535
-        * we can revisit this by using an alternative transfer
-        * method - ideally this would get done without any more
-        * interaction...
-        */
-       if (tfr->len > 65535) {
-               dev_warn_once(&spi->dev,
-                             "transfer size of %d too big for dma-transfer\n",
-                             tfr->len);
-               return false;
-       }
-
        /* if we run rx/tx_buf with word aligned addresses then we are OK */
        if ((((size_t)tfr->rx_buf & 3) == 0) &&
            (((size_t)tfr->tx_buf & 3) == 0))
@@ -461,7 +448,7 @@ static void bcm2835_dma_init(struct spi_master *master, 
struct device *dev)
 
        /* all went well, so set can_dma */
        master->can_dma = bcm2835_spi_can_dma;
-       master->max_dma_len = 65535; /* limitation by BCM2835_SPI_DLEN */
+       master->max_dma_len = 65528; /* limitation by BCM2835_SPI_DLEN */
        /* need to do TX AND RX DMA, so we need dummy buffers */
        master->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;
 
-- 
2.11.0

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